the search of dark matter with ardm detector
DESCRIPTION
CRACOW EPIPHANY CONFERENCE ON NEUTRINOS AND DARK MATTER 5 - 8 January 2006, Cracow, Poland. The search of dark matter with ArDM detector. Piotr Mijakowski The Andrzej Sołtan Institute For Nuclear Studies (IPJ), Warsaw, Świerk. OUTLINE. I ArDM ( Ar gon D ark M atter) - PowerPoint PPT PresentationTRANSCRIPT
The search of dark matter with ArDM detector
Piotr MijakowskiThe Andrzej Sołtan Institute For Nuclear Studies (IPJ) Warsaw Świerk
CRACOW EPIPHANY CONFERENCE ON NEUTRINOS AND DARK MATTER5 - 8 January 2006 Cracow Poland
PMijakowski Young Researchers Session 8 January 2006 Cracow 2
OUTLINE
I ArDM (Argon Dark Matter)
II Neutron background in dark matter underground searches
III Geant4 neutron background studies
PMijakowski Young Researchers Session 8 January 2006 Cracow 3
part I ndash ArDM
httpneutrinoethzchArDM
ArDM a proposed ton-scale liquid Argon experiment for direct detection of Dark Matter as WIMPs (Weakly Interacting Massive
Particle )
ABadertscher RChandrasekharan LKaufmann AKnecht LKnechtMLaffranchi MMessina GNatterer POtiougova ARubbia JUlbricht
ETH Zurich Switzerland
CAmsler CRegenfus ABuechler-GermannZurich University Switzerland
ABueno MCCarmona-Benitez JLozano-Bahilo SNavas-ConchaUniversity of Granada Spain
IGil-Botella PLadron de Guevara LRomeroCIEMAT Spain
TKozłowski PMijakowski ERondioSoltan Institute (IPJ) Warsaw-Świerk Poland
HChagani EDaw PMajewski VKudryavtsev NSpoonerUniversity of Sheffield England
PMijakowski Young Researchers Session 8 January 2006 Cracow 4
ArDM (cont)
Elastic scattering reaction
+ Arat rest + Arrecoil
ArDMCERN
170
cm
LEM
PMTs
Ar
(10 cm)
LAr(120 cm)
detector design
drift field asymp 4 kVcm
bull Measurement of the recoils of target nuclei [10-100 keV]bull Recoil energy scintillation amp ionization of Argon
GOAL independently detect the light (PMTs) and the charge (Large Electron Multiplier)
bull lightcharge ratio allows to discriminate background events (e vs nuclear recoils)
PMijakowski Young Researchers Session 8 January 2006 Cracow 5
ArDM status
RampD CERN (1 ton prototype)
bull High voltage systembull LEM based charge readoutbull Light detection system (PMTs + VUV reflecting mirrors)bull CAD design and assemby of the detector
KEY POINT UNDERSTAND THE DETECTOR PERFORMANCE
FIRST GOAL proof of principle 39Ar rejection (intrinsic background beta-emitter with decay rate of asymp 1 kHz in a 1 ton detector)
Simulations full detector geom experimental background
PMijakowski Young Researchers Session 8 January 2006 Cracow 6
ArDM prospects
pictures ECocciaTAUP05
TIME SCALE
2006 assembly of detector at CERN test on surface
2007 transport to the Underground Laboratory (Canfranc Spain) installation in experimental hall and mounting of infrastructure + neutron shield
2007 first data taking
CANFRANC LAB (2450 m we)
PMijakowski Young Researchers Session 8 January 2006 Cracow 7
Estimated event rates
asymp 100 eventtonday
asymp 1 eventtonday
for = 10-46asymp 1 eventton100 day
Assuming 30 keV recoil energy threshold M = 100 GeVc2
PMijakowski Young Researchers Session 8 January 2006 Cracow 8
part II ndash Neutron background
Background events
nuclear eventse-like eventspossible to discriminate
bull the same signal from WIMP amp neutron interactions
bull only possible way to distinguish neutron multiple scattering
NEUTRON BACKGROUND SOURCES
local radioactivity (surrounding rock detector components)
muon-induced neutrons
- spontaneous fission 238U
- (n) reactions rsquos from radioactive chains of UTh
MOTIVATION neutron background limits detector sensitivity to WIMPs
PMijakowski Young Researchers Session 8 January 2006 Cracow 9
Neutron background sources
1 neutrons from surrounding rock - 238U and (n) reactionsflux rock ~ 38 times 10-6 n(scm2) CANFRANC ArDM input (preliminary) ~ 13200 ndaysupression neutron shielding
2 neutrons from det components - 238U and (n) reactions flux bdquodetector dependentrdquo ArDM input (preliminary) ~ 74 ndaysupression high-purity materials
3 muon-induced neutrons ndash production in hadronic amp e-m cascades init by rsquos flux -ind ~ 17 times 10-9 n(scm2) CANFRANCArDM input (preliminary) ~ 6 ndaysupression active veto
PMijakowski Young Researchers Session 8 January 2006 Cracow 10
Neutron background energy spectra
only fission spectrum
[1] rock
[2] detector components[3] -ind
plots 1 amp 3 MJ Carson JC Davies et al Astroparticle Physics 21(2004) 667-687
PMijakowski Young Researchers Session 8 January 2006 Cracow 11
part III ndash Geant4 neutron background studies
How many neutron recoils we will have in our experiment
(how many neutrons will enter the detector what energy spectrum how many would interact and produce visible recoils how many would undergo multiple scattering)
ArDM simulation tasks
detailed detector geom (Geant4) verifiaction of sim processes
(elastic scattering neutron capture)
rock neutrons neutrons from det components muon-induced neutrons
other background sources rsquos 39Ar
full detector sim (GRANADA)
PMijakowski Young Researchers Session 8 January 2006 Cracow 12
Geant4 neutron background studies ndash elastic scattering in liquid Argon
coscos
cos~d
ddT
d
dddN ArAr
)cos1(
2)(sincos1 2
2
22
2
2
2
Arn
nArnnAr
n
Ar
Arn
nnAr
Mm
mMTmM
m
M
Mm
mTT
TnltltMn
non relativistic
Argon recoil
spectra from G4
simulation
Tn = 5 keV
Tn = 15 MeV
Tn = 2 MeV
PMijakowski Young Researchers Session 8 January 2006 Cracow 13
SIMULATION- neutron source placed randomly on the walls of fiducial volume
- neutrons going out of the detector are neglected
INPUT
neutrons from rock input energy
spectrum
Geant4 neutron background studies ndash rock neutrons analysis example
n = 38bull10-6 n(scm2)assumed total neutron flux at the
walls of fiducial volume
IN OUR GEOMETRY1 neutron per ~ 65 sec13200 neutrons per day
10 keV threshold
OUTPUT
PMijakowski Young Researchers Session 8 January 2006 Cracow 14
Geant4 neutron background studies ndash rock neutrons analysis example
no of incoming neutrons
13200 nday
- correction for interacting neutrons
Pint~ 577500 nday
- correction for multiplicity
Pmulti~ 537500 ndash 4000= 3500 nday
+ correction for spatial resolution (2 cm)
3700nday
Pinter~57 Pmulti~53
assumed 2cm spatial resolution
visible95
- shielding (CH2) reduction factor 104-106
1-135 events per year
PMijakowski Young Researchers Session 8 January 2006 Cracow 15
Summary amp Outlook
bull ArDM a new project aiming at developing and operating a 1 ton-scale liquid Argon detector for direct detection of WIMPs
bull With a 1 ton prototype we want to show the validity of this design (in particular 39Ar rejection)
bull Neutron shieldings will be addressed in a second phase
bull Investigations on neutron background sources and their interactions inside the detector are also performed (simulations in Geant4)ndash evaluation of expected number of neutron events (data analysis)ndash simulations will help to specify requirements for detector veto and
shielding
SIMULATIONS OUTLOOKbull Energy spectra and flux of incoming neutronsbull Detailed detector geometry in Geant4
BACKUP
PMijakowski Young Researchers Session 8 January 2006 Cracow 17
Geant4 neutron background studies ndash neutron capture in liquid Argon
capture on natural Argon(40Ar - 996 36Ar - 0337 38Ar - 0063)
Initial neutron energy = 10 eV
Average number of rsquos produced = 35
6099 MeV
8788 MeV
6598 MeV
PMijakowski Young Researchers Session 8 January 2006 Cracow 2
OUTLINE
I ArDM (Argon Dark Matter)
II Neutron background in dark matter underground searches
III Geant4 neutron background studies
PMijakowski Young Researchers Session 8 January 2006 Cracow 3
part I ndash ArDM
httpneutrinoethzchArDM
ArDM a proposed ton-scale liquid Argon experiment for direct detection of Dark Matter as WIMPs (Weakly Interacting Massive
Particle )
ABadertscher RChandrasekharan LKaufmann AKnecht LKnechtMLaffranchi MMessina GNatterer POtiougova ARubbia JUlbricht
ETH Zurich Switzerland
CAmsler CRegenfus ABuechler-GermannZurich University Switzerland
ABueno MCCarmona-Benitez JLozano-Bahilo SNavas-ConchaUniversity of Granada Spain
IGil-Botella PLadron de Guevara LRomeroCIEMAT Spain
TKozłowski PMijakowski ERondioSoltan Institute (IPJ) Warsaw-Świerk Poland
HChagani EDaw PMajewski VKudryavtsev NSpoonerUniversity of Sheffield England
PMijakowski Young Researchers Session 8 January 2006 Cracow 4
ArDM (cont)
Elastic scattering reaction
+ Arat rest + Arrecoil
ArDMCERN
170
cm
LEM
PMTs
Ar
(10 cm)
LAr(120 cm)
detector design
drift field asymp 4 kVcm
bull Measurement of the recoils of target nuclei [10-100 keV]bull Recoil energy scintillation amp ionization of Argon
GOAL independently detect the light (PMTs) and the charge (Large Electron Multiplier)
bull lightcharge ratio allows to discriminate background events (e vs nuclear recoils)
PMijakowski Young Researchers Session 8 January 2006 Cracow 5
ArDM status
RampD CERN (1 ton prototype)
bull High voltage systembull LEM based charge readoutbull Light detection system (PMTs + VUV reflecting mirrors)bull CAD design and assemby of the detector
KEY POINT UNDERSTAND THE DETECTOR PERFORMANCE
FIRST GOAL proof of principle 39Ar rejection (intrinsic background beta-emitter with decay rate of asymp 1 kHz in a 1 ton detector)
Simulations full detector geom experimental background
PMijakowski Young Researchers Session 8 January 2006 Cracow 6
ArDM prospects
pictures ECocciaTAUP05
TIME SCALE
2006 assembly of detector at CERN test on surface
2007 transport to the Underground Laboratory (Canfranc Spain) installation in experimental hall and mounting of infrastructure + neutron shield
2007 first data taking
CANFRANC LAB (2450 m we)
PMijakowski Young Researchers Session 8 January 2006 Cracow 7
Estimated event rates
asymp 100 eventtonday
asymp 1 eventtonday
for = 10-46asymp 1 eventton100 day
Assuming 30 keV recoil energy threshold M = 100 GeVc2
PMijakowski Young Researchers Session 8 January 2006 Cracow 8
part II ndash Neutron background
Background events
nuclear eventse-like eventspossible to discriminate
bull the same signal from WIMP amp neutron interactions
bull only possible way to distinguish neutron multiple scattering
NEUTRON BACKGROUND SOURCES
local radioactivity (surrounding rock detector components)
muon-induced neutrons
- spontaneous fission 238U
- (n) reactions rsquos from radioactive chains of UTh
MOTIVATION neutron background limits detector sensitivity to WIMPs
PMijakowski Young Researchers Session 8 January 2006 Cracow 9
Neutron background sources
1 neutrons from surrounding rock - 238U and (n) reactionsflux rock ~ 38 times 10-6 n(scm2) CANFRANC ArDM input (preliminary) ~ 13200 ndaysupression neutron shielding
2 neutrons from det components - 238U and (n) reactions flux bdquodetector dependentrdquo ArDM input (preliminary) ~ 74 ndaysupression high-purity materials
3 muon-induced neutrons ndash production in hadronic amp e-m cascades init by rsquos flux -ind ~ 17 times 10-9 n(scm2) CANFRANCArDM input (preliminary) ~ 6 ndaysupression active veto
PMijakowski Young Researchers Session 8 January 2006 Cracow 10
Neutron background energy spectra
only fission spectrum
[1] rock
[2] detector components[3] -ind
plots 1 amp 3 MJ Carson JC Davies et al Astroparticle Physics 21(2004) 667-687
PMijakowski Young Researchers Session 8 January 2006 Cracow 11
part III ndash Geant4 neutron background studies
How many neutron recoils we will have in our experiment
(how many neutrons will enter the detector what energy spectrum how many would interact and produce visible recoils how many would undergo multiple scattering)
ArDM simulation tasks
detailed detector geom (Geant4) verifiaction of sim processes
(elastic scattering neutron capture)
rock neutrons neutrons from det components muon-induced neutrons
other background sources rsquos 39Ar
full detector sim (GRANADA)
PMijakowski Young Researchers Session 8 January 2006 Cracow 12
Geant4 neutron background studies ndash elastic scattering in liquid Argon
coscos
cos~d
ddT
d
dddN ArAr
)cos1(
2)(sincos1 2
2
22
2
2
2
Arn
nArnnAr
n
Ar
Arn
nnAr
Mm
mMTmM
m
M
Mm
mTT
TnltltMn
non relativistic
Argon recoil
spectra from G4
simulation
Tn = 5 keV
Tn = 15 MeV
Tn = 2 MeV
PMijakowski Young Researchers Session 8 January 2006 Cracow 13
SIMULATION- neutron source placed randomly on the walls of fiducial volume
- neutrons going out of the detector are neglected
INPUT
neutrons from rock input energy
spectrum
Geant4 neutron background studies ndash rock neutrons analysis example
n = 38bull10-6 n(scm2)assumed total neutron flux at the
walls of fiducial volume
IN OUR GEOMETRY1 neutron per ~ 65 sec13200 neutrons per day
10 keV threshold
OUTPUT
PMijakowski Young Researchers Session 8 January 2006 Cracow 14
Geant4 neutron background studies ndash rock neutrons analysis example
no of incoming neutrons
13200 nday
- correction for interacting neutrons
Pint~ 577500 nday
- correction for multiplicity
Pmulti~ 537500 ndash 4000= 3500 nday
+ correction for spatial resolution (2 cm)
3700nday
Pinter~57 Pmulti~53
assumed 2cm spatial resolution
visible95
- shielding (CH2) reduction factor 104-106
1-135 events per year
PMijakowski Young Researchers Session 8 January 2006 Cracow 15
Summary amp Outlook
bull ArDM a new project aiming at developing and operating a 1 ton-scale liquid Argon detector for direct detection of WIMPs
bull With a 1 ton prototype we want to show the validity of this design (in particular 39Ar rejection)
bull Neutron shieldings will be addressed in a second phase
bull Investigations on neutron background sources and their interactions inside the detector are also performed (simulations in Geant4)ndash evaluation of expected number of neutron events (data analysis)ndash simulations will help to specify requirements for detector veto and
shielding
SIMULATIONS OUTLOOKbull Energy spectra and flux of incoming neutronsbull Detailed detector geometry in Geant4
BACKUP
PMijakowski Young Researchers Session 8 January 2006 Cracow 17
Geant4 neutron background studies ndash neutron capture in liquid Argon
capture on natural Argon(40Ar - 996 36Ar - 0337 38Ar - 0063)
Initial neutron energy = 10 eV
Average number of rsquos produced = 35
6099 MeV
8788 MeV
6598 MeV
PMijakowski Young Researchers Session 8 January 2006 Cracow 3
part I ndash ArDM
httpneutrinoethzchArDM
ArDM a proposed ton-scale liquid Argon experiment for direct detection of Dark Matter as WIMPs (Weakly Interacting Massive
Particle )
ABadertscher RChandrasekharan LKaufmann AKnecht LKnechtMLaffranchi MMessina GNatterer POtiougova ARubbia JUlbricht
ETH Zurich Switzerland
CAmsler CRegenfus ABuechler-GermannZurich University Switzerland
ABueno MCCarmona-Benitez JLozano-Bahilo SNavas-ConchaUniversity of Granada Spain
IGil-Botella PLadron de Guevara LRomeroCIEMAT Spain
TKozłowski PMijakowski ERondioSoltan Institute (IPJ) Warsaw-Świerk Poland
HChagani EDaw PMajewski VKudryavtsev NSpoonerUniversity of Sheffield England
PMijakowski Young Researchers Session 8 January 2006 Cracow 4
ArDM (cont)
Elastic scattering reaction
+ Arat rest + Arrecoil
ArDMCERN
170
cm
LEM
PMTs
Ar
(10 cm)
LAr(120 cm)
detector design
drift field asymp 4 kVcm
bull Measurement of the recoils of target nuclei [10-100 keV]bull Recoil energy scintillation amp ionization of Argon
GOAL independently detect the light (PMTs) and the charge (Large Electron Multiplier)
bull lightcharge ratio allows to discriminate background events (e vs nuclear recoils)
PMijakowski Young Researchers Session 8 January 2006 Cracow 5
ArDM status
RampD CERN (1 ton prototype)
bull High voltage systembull LEM based charge readoutbull Light detection system (PMTs + VUV reflecting mirrors)bull CAD design and assemby of the detector
KEY POINT UNDERSTAND THE DETECTOR PERFORMANCE
FIRST GOAL proof of principle 39Ar rejection (intrinsic background beta-emitter with decay rate of asymp 1 kHz in a 1 ton detector)
Simulations full detector geom experimental background
PMijakowski Young Researchers Session 8 January 2006 Cracow 6
ArDM prospects
pictures ECocciaTAUP05
TIME SCALE
2006 assembly of detector at CERN test on surface
2007 transport to the Underground Laboratory (Canfranc Spain) installation in experimental hall and mounting of infrastructure + neutron shield
2007 first data taking
CANFRANC LAB (2450 m we)
PMijakowski Young Researchers Session 8 January 2006 Cracow 7
Estimated event rates
asymp 100 eventtonday
asymp 1 eventtonday
for = 10-46asymp 1 eventton100 day
Assuming 30 keV recoil energy threshold M = 100 GeVc2
PMijakowski Young Researchers Session 8 January 2006 Cracow 8
part II ndash Neutron background
Background events
nuclear eventse-like eventspossible to discriminate
bull the same signal from WIMP amp neutron interactions
bull only possible way to distinguish neutron multiple scattering
NEUTRON BACKGROUND SOURCES
local radioactivity (surrounding rock detector components)
muon-induced neutrons
- spontaneous fission 238U
- (n) reactions rsquos from radioactive chains of UTh
MOTIVATION neutron background limits detector sensitivity to WIMPs
PMijakowski Young Researchers Session 8 January 2006 Cracow 9
Neutron background sources
1 neutrons from surrounding rock - 238U and (n) reactionsflux rock ~ 38 times 10-6 n(scm2) CANFRANC ArDM input (preliminary) ~ 13200 ndaysupression neutron shielding
2 neutrons from det components - 238U and (n) reactions flux bdquodetector dependentrdquo ArDM input (preliminary) ~ 74 ndaysupression high-purity materials
3 muon-induced neutrons ndash production in hadronic amp e-m cascades init by rsquos flux -ind ~ 17 times 10-9 n(scm2) CANFRANCArDM input (preliminary) ~ 6 ndaysupression active veto
PMijakowski Young Researchers Session 8 January 2006 Cracow 10
Neutron background energy spectra
only fission spectrum
[1] rock
[2] detector components[3] -ind
plots 1 amp 3 MJ Carson JC Davies et al Astroparticle Physics 21(2004) 667-687
PMijakowski Young Researchers Session 8 January 2006 Cracow 11
part III ndash Geant4 neutron background studies
How many neutron recoils we will have in our experiment
(how many neutrons will enter the detector what energy spectrum how many would interact and produce visible recoils how many would undergo multiple scattering)
ArDM simulation tasks
detailed detector geom (Geant4) verifiaction of sim processes
(elastic scattering neutron capture)
rock neutrons neutrons from det components muon-induced neutrons
other background sources rsquos 39Ar
full detector sim (GRANADA)
PMijakowski Young Researchers Session 8 January 2006 Cracow 12
Geant4 neutron background studies ndash elastic scattering in liquid Argon
coscos
cos~d
ddT
d
dddN ArAr
)cos1(
2)(sincos1 2
2
22
2
2
2
Arn
nArnnAr
n
Ar
Arn
nnAr
Mm
mMTmM
m
M
Mm
mTT
TnltltMn
non relativistic
Argon recoil
spectra from G4
simulation
Tn = 5 keV
Tn = 15 MeV
Tn = 2 MeV
PMijakowski Young Researchers Session 8 January 2006 Cracow 13
SIMULATION- neutron source placed randomly on the walls of fiducial volume
- neutrons going out of the detector are neglected
INPUT
neutrons from rock input energy
spectrum
Geant4 neutron background studies ndash rock neutrons analysis example
n = 38bull10-6 n(scm2)assumed total neutron flux at the
walls of fiducial volume
IN OUR GEOMETRY1 neutron per ~ 65 sec13200 neutrons per day
10 keV threshold
OUTPUT
PMijakowski Young Researchers Session 8 January 2006 Cracow 14
Geant4 neutron background studies ndash rock neutrons analysis example
no of incoming neutrons
13200 nday
- correction for interacting neutrons
Pint~ 577500 nday
- correction for multiplicity
Pmulti~ 537500 ndash 4000= 3500 nday
+ correction for spatial resolution (2 cm)
3700nday
Pinter~57 Pmulti~53
assumed 2cm spatial resolution
visible95
- shielding (CH2) reduction factor 104-106
1-135 events per year
PMijakowski Young Researchers Session 8 January 2006 Cracow 15
Summary amp Outlook
bull ArDM a new project aiming at developing and operating a 1 ton-scale liquid Argon detector for direct detection of WIMPs
bull With a 1 ton prototype we want to show the validity of this design (in particular 39Ar rejection)
bull Neutron shieldings will be addressed in a second phase
bull Investigations on neutron background sources and their interactions inside the detector are also performed (simulations in Geant4)ndash evaluation of expected number of neutron events (data analysis)ndash simulations will help to specify requirements for detector veto and
shielding
SIMULATIONS OUTLOOKbull Energy spectra and flux of incoming neutronsbull Detailed detector geometry in Geant4
BACKUP
PMijakowski Young Researchers Session 8 January 2006 Cracow 17
Geant4 neutron background studies ndash neutron capture in liquid Argon
capture on natural Argon(40Ar - 996 36Ar - 0337 38Ar - 0063)
Initial neutron energy = 10 eV
Average number of rsquos produced = 35
6099 MeV
8788 MeV
6598 MeV
PMijakowski Young Researchers Session 8 January 2006 Cracow 4
ArDM (cont)
Elastic scattering reaction
+ Arat rest + Arrecoil
ArDMCERN
170
cm
LEM
PMTs
Ar
(10 cm)
LAr(120 cm)
detector design
drift field asymp 4 kVcm
bull Measurement of the recoils of target nuclei [10-100 keV]bull Recoil energy scintillation amp ionization of Argon
GOAL independently detect the light (PMTs) and the charge (Large Electron Multiplier)
bull lightcharge ratio allows to discriminate background events (e vs nuclear recoils)
PMijakowski Young Researchers Session 8 January 2006 Cracow 5
ArDM status
RampD CERN (1 ton prototype)
bull High voltage systembull LEM based charge readoutbull Light detection system (PMTs + VUV reflecting mirrors)bull CAD design and assemby of the detector
KEY POINT UNDERSTAND THE DETECTOR PERFORMANCE
FIRST GOAL proof of principle 39Ar rejection (intrinsic background beta-emitter with decay rate of asymp 1 kHz in a 1 ton detector)
Simulations full detector geom experimental background
PMijakowski Young Researchers Session 8 January 2006 Cracow 6
ArDM prospects
pictures ECocciaTAUP05
TIME SCALE
2006 assembly of detector at CERN test on surface
2007 transport to the Underground Laboratory (Canfranc Spain) installation in experimental hall and mounting of infrastructure + neutron shield
2007 first data taking
CANFRANC LAB (2450 m we)
PMijakowski Young Researchers Session 8 January 2006 Cracow 7
Estimated event rates
asymp 100 eventtonday
asymp 1 eventtonday
for = 10-46asymp 1 eventton100 day
Assuming 30 keV recoil energy threshold M = 100 GeVc2
PMijakowski Young Researchers Session 8 January 2006 Cracow 8
part II ndash Neutron background
Background events
nuclear eventse-like eventspossible to discriminate
bull the same signal from WIMP amp neutron interactions
bull only possible way to distinguish neutron multiple scattering
NEUTRON BACKGROUND SOURCES
local radioactivity (surrounding rock detector components)
muon-induced neutrons
- spontaneous fission 238U
- (n) reactions rsquos from radioactive chains of UTh
MOTIVATION neutron background limits detector sensitivity to WIMPs
PMijakowski Young Researchers Session 8 January 2006 Cracow 9
Neutron background sources
1 neutrons from surrounding rock - 238U and (n) reactionsflux rock ~ 38 times 10-6 n(scm2) CANFRANC ArDM input (preliminary) ~ 13200 ndaysupression neutron shielding
2 neutrons from det components - 238U and (n) reactions flux bdquodetector dependentrdquo ArDM input (preliminary) ~ 74 ndaysupression high-purity materials
3 muon-induced neutrons ndash production in hadronic amp e-m cascades init by rsquos flux -ind ~ 17 times 10-9 n(scm2) CANFRANCArDM input (preliminary) ~ 6 ndaysupression active veto
PMijakowski Young Researchers Session 8 January 2006 Cracow 10
Neutron background energy spectra
only fission spectrum
[1] rock
[2] detector components[3] -ind
plots 1 amp 3 MJ Carson JC Davies et al Astroparticle Physics 21(2004) 667-687
PMijakowski Young Researchers Session 8 January 2006 Cracow 11
part III ndash Geant4 neutron background studies
How many neutron recoils we will have in our experiment
(how many neutrons will enter the detector what energy spectrum how many would interact and produce visible recoils how many would undergo multiple scattering)
ArDM simulation tasks
detailed detector geom (Geant4) verifiaction of sim processes
(elastic scattering neutron capture)
rock neutrons neutrons from det components muon-induced neutrons
other background sources rsquos 39Ar
full detector sim (GRANADA)
PMijakowski Young Researchers Session 8 January 2006 Cracow 12
Geant4 neutron background studies ndash elastic scattering in liquid Argon
coscos
cos~d
ddT
d
dddN ArAr
)cos1(
2)(sincos1 2
2
22
2
2
2
Arn
nArnnAr
n
Ar
Arn
nnAr
Mm
mMTmM
m
M
Mm
mTT
TnltltMn
non relativistic
Argon recoil
spectra from G4
simulation
Tn = 5 keV
Tn = 15 MeV
Tn = 2 MeV
PMijakowski Young Researchers Session 8 January 2006 Cracow 13
SIMULATION- neutron source placed randomly on the walls of fiducial volume
- neutrons going out of the detector are neglected
INPUT
neutrons from rock input energy
spectrum
Geant4 neutron background studies ndash rock neutrons analysis example
n = 38bull10-6 n(scm2)assumed total neutron flux at the
walls of fiducial volume
IN OUR GEOMETRY1 neutron per ~ 65 sec13200 neutrons per day
10 keV threshold
OUTPUT
PMijakowski Young Researchers Session 8 January 2006 Cracow 14
Geant4 neutron background studies ndash rock neutrons analysis example
no of incoming neutrons
13200 nday
- correction for interacting neutrons
Pint~ 577500 nday
- correction for multiplicity
Pmulti~ 537500 ndash 4000= 3500 nday
+ correction for spatial resolution (2 cm)
3700nday
Pinter~57 Pmulti~53
assumed 2cm spatial resolution
visible95
- shielding (CH2) reduction factor 104-106
1-135 events per year
PMijakowski Young Researchers Session 8 January 2006 Cracow 15
Summary amp Outlook
bull ArDM a new project aiming at developing and operating a 1 ton-scale liquid Argon detector for direct detection of WIMPs
bull With a 1 ton prototype we want to show the validity of this design (in particular 39Ar rejection)
bull Neutron shieldings will be addressed in a second phase
bull Investigations on neutron background sources and their interactions inside the detector are also performed (simulations in Geant4)ndash evaluation of expected number of neutron events (data analysis)ndash simulations will help to specify requirements for detector veto and
shielding
SIMULATIONS OUTLOOKbull Energy spectra and flux of incoming neutronsbull Detailed detector geometry in Geant4
BACKUP
PMijakowski Young Researchers Session 8 January 2006 Cracow 17
Geant4 neutron background studies ndash neutron capture in liquid Argon
capture on natural Argon(40Ar - 996 36Ar - 0337 38Ar - 0063)
Initial neutron energy = 10 eV
Average number of rsquos produced = 35
6099 MeV
8788 MeV
6598 MeV
PMijakowski Young Researchers Session 8 January 2006 Cracow 5
ArDM status
RampD CERN (1 ton prototype)
bull High voltage systembull LEM based charge readoutbull Light detection system (PMTs + VUV reflecting mirrors)bull CAD design and assemby of the detector
KEY POINT UNDERSTAND THE DETECTOR PERFORMANCE
FIRST GOAL proof of principle 39Ar rejection (intrinsic background beta-emitter with decay rate of asymp 1 kHz in a 1 ton detector)
Simulations full detector geom experimental background
PMijakowski Young Researchers Session 8 January 2006 Cracow 6
ArDM prospects
pictures ECocciaTAUP05
TIME SCALE
2006 assembly of detector at CERN test on surface
2007 transport to the Underground Laboratory (Canfranc Spain) installation in experimental hall and mounting of infrastructure + neutron shield
2007 first data taking
CANFRANC LAB (2450 m we)
PMijakowski Young Researchers Session 8 January 2006 Cracow 7
Estimated event rates
asymp 100 eventtonday
asymp 1 eventtonday
for = 10-46asymp 1 eventton100 day
Assuming 30 keV recoil energy threshold M = 100 GeVc2
PMijakowski Young Researchers Session 8 January 2006 Cracow 8
part II ndash Neutron background
Background events
nuclear eventse-like eventspossible to discriminate
bull the same signal from WIMP amp neutron interactions
bull only possible way to distinguish neutron multiple scattering
NEUTRON BACKGROUND SOURCES
local radioactivity (surrounding rock detector components)
muon-induced neutrons
- spontaneous fission 238U
- (n) reactions rsquos from radioactive chains of UTh
MOTIVATION neutron background limits detector sensitivity to WIMPs
PMijakowski Young Researchers Session 8 January 2006 Cracow 9
Neutron background sources
1 neutrons from surrounding rock - 238U and (n) reactionsflux rock ~ 38 times 10-6 n(scm2) CANFRANC ArDM input (preliminary) ~ 13200 ndaysupression neutron shielding
2 neutrons from det components - 238U and (n) reactions flux bdquodetector dependentrdquo ArDM input (preliminary) ~ 74 ndaysupression high-purity materials
3 muon-induced neutrons ndash production in hadronic amp e-m cascades init by rsquos flux -ind ~ 17 times 10-9 n(scm2) CANFRANCArDM input (preliminary) ~ 6 ndaysupression active veto
PMijakowski Young Researchers Session 8 January 2006 Cracow 10
Neutron background energy spectra
only fission spectrum
[1] rock
[2] detector components[3] -ind
plots 1 amp 3 MJ Carson JC Davies et al Astroparticle Physics 21(2004) 667-687
PMijakowski Young Researchers Session 8 January 2006 Cracow 11
part III ndash Geant4 neutron background studies
How many neutron recoils we will have in our experiment
(how many neutrons will enter the detector what energy spectrum how many would interact and produce visible recoils how many would undergo multiple scattering)
ArDM simulation tasks
detailed detector geom (Geant4) verifiaction of sim processes
(elastic scattering neutron capture)
rock neutrons neutrons from det components muon-induced neutrons
other background sources rsquos 39Ar
full detector sim (GRANADA)
PMijakowski Young Researchers Session 8 January 2006 Cracow 12
Geant4 neutron background studies ndash elastic scattering in liquid Argon
coscos
cos~d
ddT
d
dddN ArAr
)cos1(
2)(sincos1 2
2
22
2
2
2
Arn
nArnnAr
n
Ar
Arn
nnAr
Mm
mMTmM
m
M
Mm
mTT
TnltltMn
non relativistic
Argon recoil
spectra from G4
simulation
Tn = 5 keV
Tn = 15 MeV
Tn = 2 MeV
PMijakowski Young Researchers Session 8 January 2006 Cracow 13
SIMULATION- neutron source placed randomly on the walls of fiducial volume
- neutrons going out of the detector are neglected
INPUT
neutrons from rock input energy
spectrum
Geant4 neutron background studies ndash rock neutrons analysis example
n = 38bull10-6 n(scm2)assumed total neutron flux at the
walls of fiducial volume
IN OUR GEOMETRY1 neutron per ~ 65 sec13200 neutrons per day
10 keV threshold
OUTPUT
PMijakowski Young Researchers Session 8 January 2006 Cracow 14
Geant4 neutron background studies ndash rock neutrons analysis example
no of incoming neutrons
13200 nday
- correction for interacting neutrons
Pint~ 577500 nday
- correction for multiplicity
Pmulti~ 537500 ndash 4000= 3500 nday
+ correction for spatial resolution (2 cm)
3700nday
Pinter~57 Pmulti~53
assumed 2cm spatial resolution
visible95
- shielding (CH2) reduction factor 104-106
1-135 events per year
PMijakowski Young Researchers Session 8 January 2006 Cracow 15
Summary amp Outlook
bull ArDM a new project aiming at developing and operating a 1 ton-scale liquid Argon detector for direct detection of WIMPs
bull With a 1 ton prototype we want to show the validity of this design (in particular 39Ar rejection)
bull Neutron shieldings will be addressed in a second phase
bull Investigations on neutron background sources and their interactions inside the detector are also performed (simulations in Geant4)ndash evaluation of expected number of neutron events (data analysis)ndash simulations will help to specify requirements for detector veto and
shielding
SIMULATIONS OUTLOOKbull Energy spectra and flux of incoming neutronsbull Detailed detector geometry in Geant4
BACKUP
PMijakowski Young Researchers Session 8 January 2006 Cracow 17
Geant4 neutron background studies ndash neutron capture in liquid Argon
capture on natural Argon(40Ar - 996 36Ar - 0337 38Ar - 0063)
Initial neutron energy = 10 eV
Average number of rsquos produced = 35
6099 MeV
8788 MeV
6598 MeV
PMijakowski Young Researchers Session 8 January 2006 Cracow 6
ArDM prospects
pictures ECocciaTAUP05
TIME SCALE
2006 assembly of detector at CERN test on surface
2007 transport to the Underground Laboratory (Canfranc Spain) installation in experimental hall and mounting of infrastructure + neutron shield
2007 first data taking
CANFRANC LAB (2450 m we)
PMijakowski Young Researchers Session 8 January 2006 Cracow 7
Estimated event rates
asymp 100 eventtonday
asymp 1 eventtonday
for = 10-46asymp 1 eventton100 day
Assuming 30 keV recoil energy threshold M = 100 GeVc2
PMijakowski Young Researchers Session 8 January 2006 Cracow 8
part II ndash Neutron background
Background events
nuclear eventse-like eventspossible to discriminate
bull the same signal from WIMP amp neutron interactions
bull only possible way to distinguish neutron multiple scattering
NEUTRON BACKGROUND SOURCES
local radioactivity (surrounding rock detector components)
muon-induced neutrons
- spontaneous fission 238U
- (n) reactions rsquos from radioactive chains of UTh
MOTIVATION neutron background limits detector sensitivity to WIMPs
PMijakowski Young Researchers Session 8 January 2006 Cracow 9
Neutron background sources
1 neutrons from surrounding rock - 238U and (n) reactionsflux rock ~ 38 times 10-6 n(scm2) CANFRANC ArDM input (preliminary) ~ 13200 ndaysupression neutron shielding
2 neutrons from det components - 238U and (n) reactions flux bdquodetector dependentrdquo ArDM input (preliminary) ~ 74 ndaysupression high-purity materials
3 muon-induced neutrons ndash production in hadronic amp e-m cascades init by rsquos flux -ind ~ 17 times 10-9 n(scm2) CANFRANCArDM input (preliminary) ~ 6 ndaysupression active veto
PMijakowski Young Researchers Session 8 January 2006 Cracow 10
Neutron background energy spectra
only fission spectrum
[1] rock
[2] detector components[3] -ind
plots 1 amp 3 MJ Carson JC Davies et al Astroparticle Physics 21(2004) 667-687
PMijakowski Young Researchers Session 8 January 2006 Cracow 11
part III ndash Geant4 neutron background studies
How many neutron recoils we will have in our experiment
(how many neutrons will enter the detector what energy spectrum how many would interact and produce visible recoils how many would undergo multiple scattering)
ArDM simulation tasks
detailed detector geom (Geant4) verifiaction of sim processes
(elastic scattering neutron capture)
rock neutrons neutrons from det components muon-induced neutrons
other background sources rsquos 39Ar
full detector sim (GRANADA)
PMijakowski Young Researchers Session 8 January 2006 Cracow 12
Geant4 neutron background studies ndash elastic scattering in liquid Argon
coscos
cos~d
ddT
d
dddN ArAr
)cos1(
2)(sincos1 2
2
22
2
2
2
Arn
nArnnAr
n
Ar
Arn
nnAr
Mm
mMTmM
m
M
Mm
mTT
TnltltMn
non relativistic
Argon recoil
spectra from G4
simulation
Tn = 5 keV
Tn = 15 MeV
Tn = 2 MeV
PMijakowski Young Researchers Session 8 January 2006 Cracow 13
SIMULATION- neutron source placed randomly on the walls of fiducial volume
- neutrons going out of the detector are neglected
INPUT
neutrons from rock input energy
spectrum
Geant4 neutron background studies ndash rock neutrons analysis example
n = 38bull10-6 n(scm2)assumed total neutron flux at the
walls of fiducial volume
IN OUR GEOMETRY1 neutron per ~ 65 sec13200 neutrons per day
10 keV threshold
OUTPUT
PMijakowski Young Researchers Session 8 January 2006 Cracow 14
Geant4 neutron background studies ndash rock neutrons analysis example
no of incoming neutrons
13200 nday
- correction for interacting neutrons
Pint~ 577500 nday
- correction for multiplicity
Pmulti~ 537500 ndash 4000= 3500 nday
+ correction for spatial resolution (2 cm)
3700nday
Pinter~57 Pmulti~53
assumed 2cm spatial resolution
visible95
- shielding (CH2) reduction factor 104-106
1-135 events per year
PMijakowski Young Researchers Session 8 January 2006 Cracow 15
Summary amp Outlook
bull ArDM a new project aiming at developing and operating a 1 ton-scale liquid Argon detector for direct detection of WIMPs
bull With a 1 ton prototype we want to show the validity of this design (in particular 39Ar rejection)
bull Neutron shieldings will be addressed in a second phase
bull Investigations on neutron background sources and their interactions inside the detector are also performed (simulations in Geant4)ndash evaluation of expected number of neutron events (data analysis)ndash simulations will help to specify requirements for detector veto and
shielding
SIMULATIONS OUTLOOKbull Energy spectra and flux of incoming neutronsbull Detailed detector geometry in Geant4
BACKUP
PMijakowski Young Researchers Session 8 January 2006 Cracow 17
Geant4 neutron background studies ndash neutron capture in liquid Argon
capture on natural Argon(40Ar - 996 36Ar - 0337 38Ar - 0063)
Initial neutron energy = 10 eV
Average number of rsquos produced = 35
6099 MeV
8788 MeV
6598 MeV
PMijakowski Young Researchers Session 8 January 2006 Cracow 7
Estimated event rates
asymp 100 eventtonday
asymp 1 eventtonday
for = 10-46asymp 1 eventton100 day
Assuming 30 keV recoil energy threshold M = 100 GeVc2
PMijakowski Young Researchers Session 8 January 2006 Cracow 8
part II ndash Neutron background
Background events
nuclear eventse-like eventspossible to discriminate
bull the same signal from WIMP amp neutron interactions
bull only possible way to distinguish neutron multiple scattering
NEUTRON BACKGROUND SOURCES
local radioactivity (surrounding rock detector components)
muon-induced neutrons
- spontaneous fission 238U
- (n) reactions rsquos from radioactive chains of UTh
MOTIVATION neutron background limits detector sensitivity to WIMPs
PMijakowski Young Researchers Session 8 January 2006 Cracow 9
Neutron background sources
1 neutrons from surrounding rock - 238U and (n) reactionsflux rock ~ 38 times 10-6 n(scm2) CANFRANC ArDM input (preliminary) ~ 13200 ndaysupression neutron shielding
2 neutrons from det components - 238U and (n) reactions flux bdquodetector dependentrdquo ArDM input (preliminary) ~ 74 ndaysupression high-purity materials
3 muon-induced neutrons ndash production in hadronic amp e-m cascades init by rsquos flux -ind ~ 17 times 10-9 n(scm2) CANFRANCArDM input (preliminary) ~ 6 ndaysupression active veto
PMijakowski Young Researchers Session 8 January 2006 Cracow 10
Neutron background energy spectra
only fission spectrum
[1] rock
[2] detector components[3] -ind
plots 1 amp 3 MJ Carson JC Davies et al Astroparticle Physics 21(2004) 667-687
PMijakowski Young Researchers Session 8 January 2006 Cracow 11
part III ndash Geant4 neutron background studies
How many neutron recoils we will have in our experiment
(how many neutrons will enter the detector what energy spectrum how many would interact and produce visible recoils how many would undergo multiple scattering)
ArDM simulation tasks
detailed detector geom (Geant4) verifiaction of sim processes
(elastic scattering neutron capture)
rock neutrons neutrons from det components muon-induced neutrons
other background sources rsquos 39Ar
full detector sim (GRANADA)
PMijakowski Young Researchers Session 8 January 2006 Cracow 12
Geant4 neutron background studies ndash elastic scattering in liquid Argon
coscos
cos~d
ddT
d
dddN ArAr
)cos1(
2)(sincos1 2
2
22
2
2
2
Arn
nArnnAr
n
Ar
Arn
nnAr
Mm
mMTmM
m
M
Mm
mTT
TnltltMn
non relativistic
Argon recoil
spectra from G4
simulation
Tn = 5 keV
Tn = 15 MeV
Tn = 2 MeV
PMijakowski Young Researchers Session 8 January 2006 Cracow 13
SIMULATION- neutron source placed randomly on the walls of fiducial volume
- neutrons going out of the detector are neglected
INPUT
neutrons from rock input energy
spectrum
Geant4 neutron background studies ndash rock neutrons analysis example
n = 38bull10-6 n(scm2)assumed total neutron flux at the
walls of fiducial volume
IN OUR GEOMETRY1 neutron per ~ 65 sec13200 neutrons per day
10 keV threshold
OUTPUT
PMijakowski Young Researchers Session 8 January 2006 Cracow 14
Geant4 neutron background studies ndash rock neutrons analysis example
no of incoming neutrons
13200 nday
- correction for interacting neutrons
Pint~ 577500 nday
- correction for multiplicity
Pmulti~ 537500 ndash 4000= 3500 nday
+ correction for spatial resolution (2 cm)
3700nday
Pinter~57 Pmulti~53
assumed 2cm spatial resolution
visible95
- shielding (CH2) reduction factor 104-106
1-135 events per year
PMijakowski Young Researchers Session 8 January 2006 Cracow 15
Summary amp Outlook
bull ArDM a new project aiming at developing and operating a 1 ton-scale liquid Argon detector for direct detection of WIMPs
bull With a 1 ton prototype we want to show the validity of this design (in particular 39Ar rejection)
bull Neutron shieldings will be addressed in a second phase
bull Investigations on neutron background sources and their interactions inside the detector are also performed (simulations in Geant4)ndash evaluation of expected number of neutron events (data analysis)ndash simulations will help to specify requirements for detector veto and
shielding
SIMULATIONS OUTLOOKbull Energy spectra and flux of incoming neutronsbull Detailed detector geometry in Geant4
BACKUP
PMijakowski Young Researchers Session 8 January 2006 Cracow 17
Geant4 neutron background studies ndash neutron capture in liquid Argon
capture on natural Argon(40Ar - 996 36Ar - 0337 38Ar - 0063)
Initial neutron energy = 10 eV
Average number of rsquos produced = 35
6099 MeV
8788 MeV
6598 MeV
PMijakowski Young Researchers Session 8 January 2006 Cracow 8
part II ndash Neutron background
Background events
nuclear eventse-like eventspossible to discriminate
bull the same signal from WIMP amp neutron interactions
bull only possible way to distinguish neutron multiple scattering
NEUTRON BACKGROUND SOURCES
local radioactivity (surrounding rock detector components)
muon-induced neutrons
- spontaneous fission 238U
- (n) reactions rsquos from radioactive chains of UTh
MOTIVATION neutron background limits detector sensitivity to WIMPs
PMijakowski Young Researchers Session 8 January 2006 Cracow 9
Neutron background sources
1 neutrons from surrounding rock - 238U and (n) reactionsflux rock ~ 38 times 10-6 n(scm2) CANFRANC ArDM input (preliminary) ~ 13200 ndaysupression neutron shielding
2 neutrons from det components - 238U and (n) reactions flux bdquodetector dependentrdquo ArDM input (preliminary) ~ 74 ndaysupression high-purity materials
3 muon-induced neutrons ndash production in hadronic amp e-m cascades init by rsquos flux -ind ~ 17 times 10-9 n(scm2) CANFRANCArDM input (preliminary) ~ 6 ndaysupression active veto
PMijakowski Young Researchers Session 8 January 2006 Cracow 10
Neutron background energy spectra
only fission spectrum
[1] rock
[2] detector components[3] -ind
plots 1 amp 3 MJ Carson JC Davies et al Astroparticle Physics 21(2004) 667-687
PMijakowski Young Researchers Session 8 January 2006 Cracow 11
part III ndash Geant4 neutron background studies
How many neutron recoils we will have in our experiment
(how many neutrons will enter the detector what energy spectrum how many would interact and produce visible recoils how many would undergo multiple scattering)
ArDM simulation tasks
detailed detector geom (Geant4) verifiaction of sim processes
(elastic scattering neutron capture)
rock neutrons neutrons from det components muon-induced neutrons
other background sources rsquos 39Ar
full detector sim (GRANADA)
PMijakowski Young Researchers Session 8 January 2006 Cracow 12
Geant4 neutron background studies ndash elastic scattering in liquid Argon
coscos
cos~d
ddT
d
dddN ArAr
)cos1(
2)(sincos1 2
2
22
2
2
2
Arn
nArnnAr
n
Ar
Arn
nnAr
Mm
mMTmM
m
M
Mm
mTT
TnltltMn
non relativistic
Argon recoil
spectra from G4
simulation
Tn = 5 keV
Tn = 15 MeV
Tn = 2 MeV
PMijakowski Young Researchers Session 8 January 2006 Cracow 13
SIMULATION- neutron source placed randomly on the walls of fiducial volume
- neutrons going out of the detector are neglected
INPUT
neutrons from rock input energy
spectrum
Geant4 neutron background studies ndash rock neutrons analysis example
n = 38bull10-6 n(scm2)assumed total neutron flux at the
walls of fiducial volume
IN OUR GEOMETRY1 neutron per ~ 65 sec13200 neutrons per day
10 keV threshold
OUTPUT
PMijakowski Young Researchers Session 8 January 2006 Cracow 14
Geant4 neutron background studies ndash rock neutrons analysis example
no of incoming neutrons
13200 nday
- correction for interacting neutrons
Pint~ 577500 nday
- correction for multiplicity
Pmulti~ 537500 ndash 4000= 3500 nday
+ correction for spatial resolution (2 cm)
3700nday
Pinter~57 Pmulti~53
assumed 2cm spatial resolution
visible95
- shielding (CH2) reduction factor 104-106
1-135 events per year
PMijakowski Young Researchers Session 8 January 2006 Cracow 15
Summary amp Outlook
bull ArDM a new project aiming at developing and operating a 1 ton-scale liquid Argon detector for direct detection of WIMPs
bull With a 1 ton prototype we want to show the validity of this design (in particular 39Ar rejection)
bull Neutron shieldings will be addressed in a second phase
bull Investigations on neutron background sources and their interactions inside the detector are also performed (simulations in Geant4)ndash evaluation of expected number of neutron events (data analysis)ndash simulations will help to specify requirements for detector veto and
shielding
SIMULATIONS OUTLOOKbull Energy spectra and flux of incoming neutronsbull Detailed detector geometry in Geant4
BACKUP
PMijakowski Young Researchers Session 8 January 2006 Cracow 17
Geant4 neutron background studies ndash neutron capture in liquid Argon
capture on natural Argon(40Ar - 996 36Ar - 0337 38Ar - 0063)
Initial neutron energy = 10 eV
Average number of rsquos produced = 35
6099 MeV
8788 MeV
6598 MeV
PMijakowski Young Researchers Session 8 January 2006 Cracow 9
Neutron background sources
1 neutrons from surrounding rock - 238U and (n) reactionsflux rock ~ 38 times 10-6 n(scm2) CANFRANC ArDM input (preliminary) ~ 13200 ndaysupression neutron shielding
2 neutrons from det components - 238U and (n) reactions flux bdquodetector dependentrdquo ArDM input (preliminary) ~ 74 ndaysupression high-purity materials
3 muon-induced neutrons ndash production in hadronic amp e-m cascades init by rsquos flux -ind ~ 17 times 10-9 n(scm2) CANFRANCArDM input (preliminary) ~ 6 ndaysupression active veto
PMijakowski Young Researchers Session 8 January 2006 Cracow 10
Neutron background energy spectra
only fission spectrum
[1] rock
[2] detector components[3] -ind
plots 1 amp 3 MJ Carson JC Davies et al Astroparticle Physics 21(2004) 667-687
PMijakowski Young Researchers Session 8 January 2006 Cracow 11
part III ndash Geant4 neutron background studies
How many neutron recoils we will have in our experiment
(how many neutrons will enter the detector what energy spectrum how many would interact and produce visible recoils how many would undergo multiple scattering)
ArDM simulation tasks
detailed detector geom (Geant4) verifiaction of sim processes
(elastic scattering neutron capture)
rock neutrons neutrons from det components muon-induced neutrons
other background sources rsquos 39Ar
full detector sim (GRANADA)
PMijakowski Young Researchers Session 8 January 2006 Cracow 12
Geant4 neutron background studies ndash elastic scattering in liquid Argon
coscos
cos~d
ddT
d
dddN ArAr
)cos1(
2)(sincos1 2
2
22
2
2
2
Arn
nArnnAr
n
Ar
Arn
nnAr
Mm
mMTmM
m
M
Mm
mTT
TnltltMn
non relativistic
Argon recoil
spectra from G4
simulation
Tn = 5 keV
Tn = 15 MeV
Tn = 2 MeV
PMijakowski Young Researchers Session 8 January 2006 Cracow 13
SIMULATION- neutron source placed randomly on the walls of fiducial volume
- neutrons going out of the detector are neglected
INPUT
neutrons from rock input energy
spectrum
Geant4 neutron background studies ndash rock neutrons analysis example
n = 38bull10-6 n(scm2)assumed total neutron flux at the
walls of fiducial volume
IN OUR GEOMETRY1 neutron per ~ 65 sec13200 neutrons per day
10 keV threshold
OUTPUT
PMijakowski Young Researchers Session 8 January 2006 Cracow 14
Geant4 neutron background studies ndash rock neutrons analysis example
no of incoming neutrons
13200 nday
- correction for interacting neutrons
Pint~ 577500 nday
- correction for multiplicity
Pmulti~ 537500 ndash 4000= 3500 nday
+ correction for spatial resolution (2 cm)
3700nday
Pinter~57 Pmulti~53
assumed 2cm spatial resolution
visible95
- shielding (CH2) reduction factor 104-106
1-135 events per year
PMijakowski Young Researchers Session 8 January 2006 Cracow 15
Summary amp Outlook
bull ArDM a new project aiming at developing and operating a 1 ton-scale liquid Argon detector for direct detection of WIMPs
bull With a 1 ton prototype we want to show the validity of this design (in particular 39Ar rejection)
bull Neutron shieldings will be addressed in a second phase
bull Investigations on neutron background sources and their interactions inside the detector are also performed (simulations in Geant4)ndash evaluation of expected number of neutron events (data analysis)ndash simulations will help to specify requirements for detector veto and
shielding
SIMULATIONS OUTLOOKbull Energy spectra and flux of incoming neutronsbull Detailed detector geometry in Geant4
BACKUP
PMijakowski Young Researchers Session 8 January 2006 Cracow 17
Geant4 neutron background studies ndash neutron capture in liquid Argon
capture on natural Argon(40Ar - 996 36Ar - 0337 38Ar - 0063)
Initial neutron energy = 10 eV
Average number of rsquos produced = 35
6099 MeV
8788 MeV
6598 MeV
PMijakowski Young Researchers Session 8 January 2006 Cracow 10
Neutron background energy spectra
only fission spectrum
[1] rock
[2] detector components[3] -ind
plots 1 amp 3 MJ Carson JC Davies et al Astroparticle Physics 21(2004) 667-687
PMijakowski Young Researchers Session 8 January 2006 Cracow 11
part III ndash Geant4 neutron background studies
How many neutron recoils we will have in our experiment
(how many neutrons will enter the detector what energy spectrum how many would interact and produce visible recoils how many would undergo multiple scattering)
ArDM simulation tasks
detailed detector geom (Geant4) verifiaction of sim processes
(elastic scattering neutron capture)
rock neutrons neutrons from det components muon-induced neutrons
other background sources rsquos 39Ar
full detector sim (GRANADA)
PMijakowski Young Researchers Session 8 January 2006 Cracow 12
Geant4 neutron background studies ndash elastic scattering in liquid Argon
coscos
cos~d
ddT
d
dddN ArAr
)cos1(
2)(sincos1 2
2
22
2
2
2
Arn
nArnnAr
n
Ar
Arn
nnAr
Mm
mMTmM
m
M
Mm
mTT
TnltltMn
non relativistic
Argon recoil
spectra from G4
simulation
Tn = 5 keV
Tn = 15 MeV
Tn = 2 MeV
PMijakowski Young Researchers Session 8 January 2006 Cracow 13
SIMULATION- neutron source placed randomly on the walls of fiducial volume
- neutrons going out of the detector are neglected
INPUT
neutrons from rock input energy
spectrum
Geant4 neutron background studies ndash rock neutrons analysis example
n = 38bull10-6 n(scm2)assumed total neutron flux at the
walls of fiducial volume
IN OUR GEOMETRY1 neutron per ~ 65 sec13200 neutrons per day
10 keV threshold
OUTPUT
PMijakowski Young Researchers Session 8 January 2006 Cracow 14
Geant4 neutron background studies ndash rock neutrons analysis example
no of incoming neutrons
13200 nday
- correction for interacting neutrons
Pint~ 577500 nday
- correction for multiplicity
Pmulti~ 537500 ndash 4000= 3500 nday
+ correction for spatial resolution (2 cm)
3700nday
Pinter~57 Pmulti~53
assumed 2cm spatial resolution
visible95
- shielding (CH2) reduction factor 104-106
1-135 events per year
PMijakowski Young Researchers Session 8 January 2006 Cracow 15
Summary amp Outlook
bull ArDM a new project aiming at developing and operating a 1 ton-scale liquid Argon detector for direct detection of WIMPs
bull With a 1 ton prototype we want to show the validity of this design (in particular 39Ar rejection)
bull Neutron shieldings will be addressed in a second phase
bull Investigations on neutron background sources and their interactions inside the detector are also performed (simulations in Geant4)ndash evaluation of expected number of neutron events (data analysis)ndash simulations will help to specify requirements for detector veto and
shielding
SIMULATIONS OUTLOOKbull Energy spectra and flux of incoming neutronsbull Detailed detector geometry in Geant4
BACKUP
PMijakowski Young Researchers Session 8 January 2006 Cracow 17
Geant4 neutron background studies ndash neutron capture in liquid Argon
capture on natural Argon(40Ar - 996 36Ar - 0337 38Ar - 0063)
Initial neutron energy = 10 eV
Average number of rsquos produced = 35
6099 MeV
8788 MeV
6598 MeV
PMijakowski Young Researchers Session 8 January 2006 Cracow 11
part III ndash Geant4 neutron background studies
How many neutron recoils we will have in our experiment
(how many neutrons will enter the detector what energy spectrum how many would interact and produce visible recoils how many would undergo multiple scattering)
ArDM simulation tasks
detailed detector geom (Geant4) verifiaction of sim processes
(elastic scattering neutron capture)
rock neutrons neutrons from det components muon-induced neutrons
other background sources rsquos 39Ar
full detector sim (GRANADA)
PMijakowski Young Researchers Session 8 January 2006 Cracow 12
Geant4 neutron background studies ndash elastic scattering in liquid Argon
coscos
cos~d
ddT
d
dddN ArAr
)cos1(
2)(sincos1 2
2
22
2
2
2
Arn
nArnnAr
n
Ar
Arn
nnAr
Mm
mMTmM
m
M
Mm
mTT
TnltltMn
non relativistic
Argon recoil
spectra from G4
simulation
Tn = 5 keV
Tn = 15 MeV
Tn = 2 MeV
PMijakowski Young Researchers Session 8 January 2006 Cracow 13
SIMULATION- neutron source placed randomly on the walls of fiducial volume
- neutrons going out of the detector are neglected
INPUT
neutrons from rock input energy
spectrum
Geant4 neutron background studies ndash rock neutrons analysis example
n = 38bull10-6 n(scm2)assumed total neutron flux at the
walls of fiducial volume
IN OUR GEOMETRY1 neutron per ~ 65 sec13200 neutrons per day
10 keV threshold
OUTPUT
PMijakowski Young Researchers Session 8 January 2006 Cracow 14
Geant4 neutron background studies ndash rock neutrons analysis example
no of incoming neutrons
13200 nday
- correction for interacting neutrons
Pint~ 577500 nday
- correction for multiplicity
Pmulti~ 537500 ndash 4000= 3500 nday
+ correction for spatial resolution (2 cm)
3700nday
Pinter~57 Pmulti~53
assumed 2cm spatial resolution
visible95
- shielding (CH2) reduction factor 104-106
1-135 events per year
PMijakowski Young Researchers Session 8 January 2006 Cracow 15
Summary amp Outlook
bull ArDM a new project aiming at developing and operating a 1 ton-scale liquid Argon detector for direct detection of WIMPs
bull With a 1 ton prototype we want to show the validity of this design (in particular 39Ar rejection)
bull Neutron shieldings will be addressed in a second phase
bull Investigations on neutron background sources and their interactions inside the detector are also performed (simulations in Geant4)ndash evaluation of expected number of neutron events (data analysis)ndash simulations will help to specify requirements for detector veto and
shielding
SIMULATIONS OUTLOOKbull Energy spectra and flux of incoming neutronsbull Detailed detector geometry in Geant4
BACKUP
PMijakowski Young Researchers Session 8 January 2006 Cracow 17
Geant4 neutron background studies ndash neutron capture in liquid Argon
capture on natural Argon(40Ar - 996 36Ar - 0337 38Ar - 0063)
Initial neutron energy = 10 eV
Average number of rsquos produced = 35
6099 MeV
8788 MeV
6598 MeV
PMijakowski Young Researchers Session 8 January 2006 Cracow 12
Geant4 neutron background studies ndash elastic scattering in liquid Argon
coscos
cos~d
ddT
d
dddN ArAr
)cos1(
2)(sincos1 2
2
22
2
2
2
Arn
nArnnAr
n
Ar
Arn
nnAr
Mm
mMTmM
m
M
Mm
mTT
TnltltMn
non relativistic
Argon recoil
spectra from G4
simulation
Tn = 5 keV
Tn = 15 MeV
Tn = 2 MeV
PMijakowski Young Researchers Session 8 January 2006 Cracow 13
SIMULATION- neutron source placed randomly on the walls of fiducial volume
- neutrons going out of the detector are neglected
INPUT
neutrons from rock input energy
spectrum
Geant4 neutron background studies ndash rock neutrons analysis example
n = 38bull10-6 n(scm2)assumed total neutron flux at the
walls of fiducial volume
IN OUR GEOMETRY1 neutron per ~ 65 sec13200 neutrons per day
10 keV threshold
OUTPUT
PMijakowski Young Researchers Session 8 January 2006 Cracow 14
Geant4 neutron background studies ndash rock neutrons analysis example
no of incoming neutrons
13200 nday
- correction for interacting neutrons
Pint~ 577500 nday
- correction for multiplicity
Pmulti~ 537500 ndash 4000= 3500 nday
+ correction for spatial resolution (2 cm)
3700nday
Pinter~57 Pmulti~53
assumed 2cm spatial resolution
visible95
- shielding (CH2) reduction factor 104-106
1-135 events per year
PMijakowski Young Researchers Session 8 January 2006 Cracow 15
Summary amp Outlook
bull ArDM a new project aiming at developing and operating a 1 ton-scale liquid Argon detector for direct detection of WIMPs
bull With a 1 ton prototype we want to show the validity of this design (in particular 39Ar rejection)
bull Neutron shieldings will be addressed in a second phase
bull Investigations on neutron background sources and their interactions inside the detector are also performed (simulations in Geant4)ndash evaluation of expected number of neutron events (data analysis)ndash simulations will help to specify requirements for detector veto and
shielding
SIMULATIONS OUTLOOKbull Energy spectra and flux of incoming neutronsbull Detailed detector geometry in Geant4
BACKUP
PMijakowski Young Researchers Session 8 January 2006 Cracow 17
Geant4 neutron background studies ndash neutron capture in liquid Argon
capture on natural Argon(40Ar - 996 36Ar - 0337 38Ar - 0063)
Initial neutron energy = 10 eV
Average number of rsquos produced = 35
6099 MeV
8788 MeV
6598 MeV
PMijakowski Young Researchers Session 8 January 2006 Cracow 13
SIMULATION- neutron source placed randomly on the walls of fiducial volume
- neutrons going out of the detector are neglected
INPUT
neutrons from rock input energy
spectrum
Geant4 neutron background studies ndash rock neutrons analysis example
n = 38bull10-6 n(scm2)assumed total neutron flux at the
walls of fiducial volume
IN OUR GEOMETRY1 neutron per ~ 65 sec13200 neutrons per day
10 keV threshold
OUTPUT
PMijakowski Young Researchers Session 8 January 2006 Cracow 14
Geant4 neutron background studies ndash rock neutrons analysis example
no of incoming neutrons
13200 nday
- correction for interacting neutrons
Pint~ 577500 nday
- correction for multiplicity
Pmulti~ 537500 ndash 4000= 3500 nday
+ correction for spatial resolution (2 cm)
3700nday
Pinter~57 Pmulti~53
assumed 2cm spatial resolution
visible95
- shielding (CH2) reduction factor 104-106
1-135 events per year
PMijakowski Young Researchers Session 8 January 2006 Cracow 15
Summary amp Outlook
bull ArDM a new project aiming at developing and operating a 1 ton-scale liquid Argon detector for direct detection of WIMPs
bull With a 1 ton prototype we want to show the validity of this design (in particular 39Ar rejection)
bull Neutron shieldings will be addressed in a second phase
bull Investigations on neutron background sources and their interactions inside the detector are also performed (simulations in Geant4)ndash evaluation of expected number of neutron events (data analysis)ndash simulations will help to specify requirements for detector veto and
shielding
SIMULATIONS OUTLOOKbull Energy spectra and flux of incoming neutronsbull Detailed detector geometry in Geant4
BACKUP
PMijakowski Young Researchers Session 8 January 2006 Cracow 17
Geant4 neutron background studies ndash neutron capture in liquid Argon
capture on natural Argon(40Ar - 996 36Ar - 0337 38Ar - 0063)
Initial neutron energy = 10 eV
Average number of rsquos produced = 35
6099 MeV
8788 MeV
6598 MeV
PMijakowski Young Researchers Session 8 January 2006 Cracow 14
Geant4 neutron background studies ndash rock neutrons analysis example
no of incoming neutrons
13200 nday
- correction for interacting neutrons
Pint~ 577500 nday
- correction for multiplicity
Pmulti~ 537500 ndash 4000= 3500 nday
+ correction for spatial resolution (2 cm)
3700nday
Pinter~57 Pmulti~53
assumed 2cm spatial resolution
visible95
- shielding (CH2) reduction factor 104-106
1-135 events per year
PMijakowski Young Researchers Session 8 January 2006 Cracow 15
Summary amp Outlook
bull ArDM a new project aiming at developing and operating a 1 ton-scale liquid Argon detector for direct detection of WIMPs
bull With a 1 ton prototype we want to show the validity of this design (in particular 39Ar rejection)
bull Neutron shieldings will be addressed in a second phase
bull Investigations on neutron background sources and their interactions inside the detector are also performed (simulations in Geant4)ndash evaluation of expected number of neutron events (data analysis)ndash simulations will help to specify requirements for detector veto and
shielding
SIMULATIONS OUTLOOKbull Energy spectra and flux of incoming neutronsbull Detailed detector geometry in Geant4
BACKUP
PMijakowski Young Researchers Session 8 January 2006 Cracow 17
Geant4 neutron background studies ndash neutron capture in liquid Argon
capture on natural Argon(40Ar - 996 36Ar - 0337 38Ar - 0063)
Initial neutron energy = 10 eV
Average number of rsquos produced = 35
6099 MeV
8788 MeV
6598 MeV
PMijakowski Young Researchers Session 8 January 2006 Cracow 15
Summary amp Outlook
bull ArDM a new project aiming at developing and operating a 1 ton-scale liquid Argon detector for direct detection of WIMPs
bull With a 1 ton prototype we want to show the validity of this design (in particular 39Ar rejection)
bull Neutron shieldings will be addressed in a second phase
bull Investigations on neutron background sources and their interactions inside the detector are also performed (simulations in Geant4)ndash evaluation of expected number of neutron events (data analysis)ndash simulations will help to specify requirements for detector veto and
shielding
SIMULATIONS OUTLOOKbull Energy spectra and flux of incoming neutronsbull Detailed detector geometry in Geant4
BACKUP
PMijakowski Young Researchers Session 8 January 2006 Cracow 17
Geant4 neutron background studies ndash neutron capture in liquid Argon
capture on natural Argon(40Ar - 996 36Ar - 0337 38Ar - 0063)
Initial neutron energy = 10 eV
Average number of rsquos produced = 35
6099 MeV
8788 MeV
6598 MeV
BACKUP
PMijakowski Young Researchers Session 8 January 2006 Cracow 17
Geant4 neutron background studies ndash neutron capture in liquid Argon
capture on natural Argon(40Ar - 996 36Ar - 0337 38Ar - 0063)
Initial neutron energy = 10 eV
Average number of rsquos produced = 35
6099 MeV
8788 MeV
6598 MeV
PMijakowski Young Researchers Session 8 January 2006 Cracow 17
Geant4 neutron background studies ndash neutron capture in liquid Argon
capture on natural Argon(40Ar - 996 36Ar - 0337 38Ar - 0063)
Initial neutron energy = 10 eV
Average number of rsquos produced = 35
6099 MeV
8788 MeV
6598 MeV