astroparticle physics at gran sasso underground laboratory: borexino and geo-neutrino
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Astroparticle Physics at Gran Sasso Underground Laboratory: Borexino and geo-neutrino. Lino Miramonti – 7 Feb 2006 - Honolulu (Hawaii). Astroparticle Physics. Astrophysics & Cosmology. Particle physics. Astroparticle physics. - PowerPoint PPT PresentationTRANSCRIPT
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Astroparticle Physics at
Gran Sasso Underground Laboratory:Borexino and geo-neutrino
Lino Miramonti – 7 Feb 2006 - Honolulu (Hawaii)
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Particle physics
Astrophysics&
Cosmology
Astroparticlephysics
Astroparticle Physics
Typical studies of astroparticle physics are:
Neutrino Physics (Solar, Supernova, Atmospherics, Geoneutrinos, neutrinos from reactors and from accelerators, etc..)
Cosmic Ray Physics Rare Processes (double beta decay, proton decay etc..) Dark Matter (WIMP’s) Gravitational Waves Nuclear Physics (Cross section measurements of astrophysics
interest) …….
Typical studies of astroparticle physics are:
Neutrino Physics (Solar, Supernova, Atmospherics, Geoneutrinos, neutrinos from reactors and from accelerators, etc..)
Cosmic Ray Physics Rare Processes (double beta decay, proton decay etc..) Dark Matter (WIMP’s) Gravitational Waves Nuclear Physics (Cross section measurements of astrophysics
interest) …….
Very little cross sections and/or very rare processes of events means to locate detector apparatus to the shelter from cosmic radiation
UndergroundPhysics
Employs knowledges and techniques from particle physics in order to study cosmological and astrophysical aspects.
Detects particles coming from space for particle physics studies.
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France Commissariat a l’Energie Atomique,
Centre National de la Recherche Scientifique
Italy Istituto Nazionale di Fisica Nucleare,
Istituto di Fotonica e Nanotecnologie Trento,
European Gravitational Observatory
Germany Max Planck Institut für Kernphysik, Technische
Universität München,
Max Planck Institut für Physik Muenchen, Eberhardt,
Karls Universität Tubingen
Spain Zaragoza University
UK Sheffield University,
Glasgow University,
London University
Czech Rep Czech Technical Univ. in Prague
Denmark University of Southern Denmark
Netherland Leiden University
Finland University of Jyväskylä
Slovakia Comenius University Bratislavia
Greece Aristot University of Thessaloniki
Integrated Large
Infrastructures
for
Astroparticle Science
ILIAS is an initiative supported by the
European Union with the aim to support the European large infrastructures operating in the astroparticle physics sector.
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The ILIAS project is based on 3 groups of activitiesactivities:
• Networking Activities
(N2) Deep Underground science laboratories(N3) Direct dark matter detection(N4) Search on double beta decay(N5) Gravitational wave research(N6) Theoretical astroparticle physics
• Joint Research Activities (R&D Projects)
(JRA1JRA1) Low background techniques for Deep Underground ScienceLow background techniques for Deep Underground Science(JRA2) Double beta decay European observatory(JRA3) Study of thermal noise reduction in gravitational wave detectors
• Transnational Access Activities
(TA1) Access to the EU Deep Underground Laboratories
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JRA1 JRA1 ((Joint Research Activities 1))
Low background techniques for deep underground sciences ( (LBT-DUSLLBT-DUSL))
ObjectivesObjectives::
Background identification and measurement (Background identification and measurement ( intrinsicintrinsic, , inducedinduced, , environmentalenvironmental))
Background rejection techniques (Background rejection techniques (shieldingshielding, , vetoesvetoes, , discriminationdiscrimination))
ObjectivesObjectives::
Background identification and measurement (Background identification and measurement ( intrinsicintrinsic, , inducedinduced, , environmentalenvironmental))
Background rejection techniques (Background rejection techniques (shieldingshielding, , vetoesvetoes, , discriminationdiscrimination))
A vast R&D programme on the improvement and implementation of ultra-low background techniques will be carried out cooperatively in the 5 European Underground Laboratories.
A vast R&D programme on the improvement and implementation of ultra-low background techniques will be carried out cooperatively in the 5 European Underground Laboratories.
Working packages
WP1: Measurements of the backgrounds in the underground labs
WP2: Implementation of background MC simulation codes
WP3: Ultra-low background techniques and facilities
WP4: Radiopurity of materials and purification techniques
Working packages
WP1: Measurements of the backgrounds in the underground labs
WP2: Implementation of background MC simulation codes
WP3: Ultra-low background techniques and facilities
WP4: Radiopurity of materials and purification techniques
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http://www.lngs.infn.it/
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LNGS permanent staff: 60 (physicists, technicians, administration)Scientists involved in LNGS experiments: 700 from 24 countries
LNGS
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Operating Institution
Istituto Nazionale di Fisica Nucleare (INFN)
Location Gran Sasso Tunnel (Abruzzi, Italy)
Excavation 1987
Underground area 3 halls A B C (100m x 18m x 20m) + service tunnels
Depth 1400 m (3800 mwe)
Total volume 180000 m3
Surface > 6000 m2
3 main halls
A B C 100 x 18 m2 (h.20 m)
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Muon Flux
1.1 μ m-2 h-1
Primordial Radionuclides
238U 6.8 ppm Rock (Hall A)
0.42 ppm Rock (Hall B)
0.66 ppm Rock (Hall C)
1.05 ppm Concrete All Halls
232Th 2.167 ppm Rock (Hall A)
0.062 ppm Rock (Hall B)
0.066 ppm Rock (Hall C)
0.656 ppm Concrete All Halls
K 160 ppm Rock
Neutron Flux
1.08 10-6 n cm-2 s-1 (0-0.05 eV)
1.84 10-6 n cm-2 s-1 (0.05 eV- 1 keV)
0.54 10-6 n cm-2 s-1 (1 keV-2.5 MeV)
0.32 10-6 n cm-2 s-1 (> 2.5 MeV)
Backgrounds & Facilities @ LNGS
Residual muon flux(6 order of magnitude lower than surface)
Coming from spontaneus fission (in particular from 238U) and (α,n) reaction on light elements in the rock
also µ-induced neutrons
Troublesome for anti-ν detection by Cowan-Reines reaction!
Rock of Hall A is 10 times more radioactive in 238U than Hall B and Hall C (and 30 times more radioactive in 232Th)
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HPGe Hall(32 m2 floor)
FACILITY FOR LOW-LEVEL RADIOACTIVITY MEASUREMENTS
Present: 32 m2 on one floor in service tunnelFuture: 60 m2 distributed on three floors in hall A
Courtesy by Matthias.Laubenstein
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Completed experiments
Atm ν, Monopoles MACRO (Streamer tubes + Liquid scintillators)Solar neutrinos GALLEX / GNO (~ 30 T Gallium radiochemical detector)ββ Heidelberg-Moscow (~ 11 kg enriched 76Ge detectors)
Mibeta (~ 7 kg Bolometers TeO2)Dark Matter DAMA (~ 100 kg NaI detectors)
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Running experiments
ββ Cuoricino (~ 41 kg TeO2 crystals)Dark Matter CRESST (Sapphire cryodetector & CaWO4 crystals (phonons+scintillation))
LIBRA (~ 250 kg NaI crystals)HDMS / Genius-TF (Ge detector 73Ge enriched)
Supernova neutrinos LVD (Streamer tubes + Liquid scintillator)Nuclear astrophysics LUNA (Accelerator)
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Under construction
CERN-GS beam ν OPERA (Emulsion)ICARUS (~ 600 T Liquid Argon)
Solar Neutrinos Borexino (~ 300 T Liquid scintillator)
Planned & proposed
ββ CUORE (~ 750 kg Te02)GERDA (76Ge)
Nuclear astrophysics LUNA-IIIGravitational waves LISA R&DDark matter Liquid Xe / Liquid Ar
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RADIOCHEMICALIntegrated in energy and time
CHERENKOVLess than 0.01% of the solar neutrino flux is been measured in real time.The main goal of Borexino is the
measurement in real time of the low energy component of solar neutrinos.
The main goal of Borexino is the measurement in real time of the low energy component of solar neutrinos.
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Borexino Collaboration
– Italy (INFN & Universiy of Milano and Genova, Perugia Univ., LNGS)
– USA (Princeton Univ., Virginia Tech.)
– Russia (RRC KI, JINR, INP MSU, INP St. Petersburg)
– Germany (Hiedelberg MPI, Munich Technical University)
– France (College de France)
– Hungary (Research Institute for Particle & Nuclear Physics)
– Poland (Institute of Physics, Jaegollian University, Cracow)
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BOREXINO: subsystemsScintillator purification systems:Water extractionVacuum distillationSilicagel adsorption
DI Water plant
Storage tanks: 300tons of PC
Borexino detector
Control roomCounting room
CTF
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Core of the detector: 300 tons of liquid scintillator (PC+PPO) contained in a nylon vessel of 8.5 m diameter. The thickness of nylon is 125 µm.
1st shield: 1000 tons of ultra-pure buffer liquid (pure PC) contained in a stainless steel sphere of 13.7 m diameter (SSS).
2200 photomultiplier tubes pointing towards the center to view the light emitted by the scintillator.
2nd shield: 2400 tons of ultra-pure water contained in a cylindrical dome.
200 photomultiplier tubes mounted on the SSS pointing outwards to detect Cerenkov light emitted in the water by muons.
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eLieBe 77
Eν = 862 keV (monochromatic)
ΦSSM = 4.8 · 109 ν s-1 cm2
e
xRecoil nuclear energy of the e-
expected rate (LMA hypothesis) is 35 counts/day in the 250-800 keV energy range
)1(10 244 MeVatcm
ee xx
Elastic Scattering
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18 m
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Cleen Room (on top of the Water Tank) for the insertions of lasers and sources for calibrations.
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Cleen Room (on top of the Water Tank) for the insertions of lasers and sources for calibrations.
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100 PMTs
4 tons of scintillator
4.5m thickness of water shield
Muon-veto detector
100 PMTs
4 tons of scintillator
4.5m thickness of water shield
Muon-veto detector
CTF is a prototype of Borexino. Its main goal was to verify the capability to reach the very low-levels of contamination needed for Borexino
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The CTF as a tool for tuning the The CTF as a tool for tuning the apparatus before fillingapparatus before filling
In this moment we use the CTF in orderIn this moment we use the CTF in order: To asses the performances of the different BOREXINO sub-systems.
To test the 14C content in the PC
To test the efficiency of the purification methods (Water extraction, Vacuum distillation, Silicagel adsorption)
To test the cleanliness of the apparatus
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1. Natural radioactivity
2. Muon Induced reactions
3. Cosmogenic induced isotopes
4. 14C
5. Air contaminants: 222Rn, 85Kr, 39Ar
1. Natural radioactivity
2. Muon Induced reactions
3. Cosmogenic induced isotopes
4. 14C
5. Air contaminants: 222Rn, 85Kr, 39Ar
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Primordial radioactivity: ( about 20 radioisotopes with half-life > Earth life)
between them:238U and 232Th (α and β emitters)40K (β emitter with end-point = 1.3 MeV)
• Selection of materials
• Surface treatment to avoid dust and particulate
• Purification: • Water extraction, • Vacuum distillation, • Ultra filtration• Nitrogen sparging
• Selection of materials
• Surface treatment to avoid dust and particulate
• Purification: • Water extraction, • Vacuum distillation, • Ultra filtration• Nitrogen sparging
• Alpha/Beta Discrimination
• Delayed Coincidence
• Alpha/Beta Discrimination
• Delayed Coincidence
Natural radioactivity
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Typical Conc. Borexino level
238U, 232Th ~ 1ppm in dust
~ 1ppb stainless steel
~ 1ppt IV nylon
~ 10-16g/g (PC)
~ 10-14g/g (water)
Knat ~ 1ppm in dust < 10-13g/g (PC)
Purification of the Scintillator (with US Skids):
•Water extraction: Impurity with high solubility in aqueous phase such as K and heavy metals in U Th chains. •Vacuum distillation: Low volatility components such as metals and dust particles.
•Ultra filtration: Particle dust.
•Nitrogen stripping: Nobles gases.
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The excitation of the scintillator depends on many factors including the energy loss density – a large dE/dx enhances the slow component of the decay curve
The ratio tail over total is expected to be greater for alpha than for electrons
Tail/Total charge ratio
An efficiency for alpha identification of ~ 97% at 751 keV with an associated beta misidentification of ~ 2.5%.
At low energies (300-600 keV) the alpha I dentification efficiency range from 90 to 97 % with an associated beta misidentification of ~ 10%.
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222Rn
218Po
214Pb 214Bi 214Po
210Pb
T=163 µs
α=5.49 MeV
α=6.02 MeV
α=7.69 MeV
210Bi 210Po
210Pb
α=5.30 MeV
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220Rn
216Po
212Pb 212Bi 212Po
208Pb
T=19.8 m
T=0.3 µs
208Tl
224Ra
α=5.68 MeV
α=6.29 MeV
α=6.792 MeV
α=8.79 MeVα=6.04 MeV
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Muon Induced reactions
At LNGS we have 1.1 µ m2 h-1 with a <Eµ> = 320 GeV
11Be τ = 13.8 s β-
7Be τ = 53.3 d β- EC
11C τ = 20.4 m β- EC
10C τ = 19.3 s β- EC
These elements having a τ > 1 s is not possible to tag them
Interacting with 12C of the organic scintillator they give:
A muon-veto system (The outer water shielding serves at the same time as water Cerenkov detector for
atmospheric muons) reduce this number by a factor 5000-10000
Ultrarelativistic µ can produce n which after been captured by p give a 2.2 MeV γ ray:
)2.2( MeVdpn
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Cosmogenic induced isotopes
XBeCn 712
During transportation, pseudocumene is exposed to cosmic neutrons.Pseudocumene is produced in Sardinia and the voyage to LNGS take about one day.During transportation cosmic neutrons interact with 12C producing 7Be:
Be-7 decays by electron capture to Li-7 and emits (with a 10.52% branching fraction) a 478 keV gamma. This line is a potential background in the Borexino neutrino window.
Theoretical sea-level Cosmic Ray Flux(Latitude New York City ≈ LNGS)
7Be is efficiently removed by distillation!
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14C
Typical Conc. Borexino level
14C/ 12C < 10-12 14C/ 12C ~ 10-18
The 14C content depend on the site of extraction. There is no possibility to eliminate this radionuclide, the only thing we can do, is to test, in CTF, samples of pseudocumene before to transport it to LNGS.
Our threshold (at 250 keV) is due to the 14C!
The reactions expected to contribute the most to 14C production in deep underground geological formations are:
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Air contaminants: 222Rn, 85Kr, 39Ar Regular N2
High Purity N2
LAK (Low Ar/Kr content) N2
N2 used to sparge scintillator
Origin Typical Conc. (in air)
Borexino
level
222Rn 238U chain 10-100 Bq/m3 ~ 70 Bq/m3 in PC
85KrAnthropogenic origin (nuclear fue reprocessing)
1 Bq/m³ 0.16 0.16 Bq/mBq/m33 in N in N22
39Ar Cosmogenic production 11 mBq/m³ 0.5 0.5 Bq/mBq/m33 in N in N22
85Krβ emitter: Emax = 687 keV (Eγ = 514 keV)Half-life: 10.8 years
39Arβ emitter: Emax = 565 keV (no gamma)Half-life: 269 years
To reduce the effect of emanation we used only electroplisched stainless steel, applied orbital weldings .
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Liquid Nitrogen (commercial quality 4.0, i.e. 99,99%) is delivered with a truck and stored on site in three tanks of 6 m³. The tanks can be refilled without interrupting the nitrogen supply.
•For Standard Purity N2 the liquid nitrogen is simply evaporated. The gas passes through a heat exchanger to keep it at constant temperature of ca. 15°C. The level of 222Rn is usually in the range of 0.1 – 0.2 mBq/m³ (STP).
•For the High Purity N2 the liquid nitrogen passes through a cryogenic adsorption trap ("LTA" = Low Temperature Absorber), filled with 11.5 liters of activated carbon. (We use CarboAct F3/F4, which was found to be very low in 226Ra (less than 0,3 mBq/kg)). For the evaporation we use an electrical evaporator with only low surface. The level of 222Rn is usually is below 1 µBq/m³ (STP). The output can be up to 100 m³/h.
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Deionization Unit
Reverse Osmisis
Nitrogen StrippingUltra Filters
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Schematic of the scintillator purification system for CTF. The scintillator is either water extracted, or vacuum distilled then filtered and stripped with nitrogen before being returned to the scintillator containment vessel.
The purification system was constructed entirely of electropolished stainless steel, quartz and teflon
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Installation of the US Skids
Lino Miramonti - 7 February 2006 - Honolulu Hawaii (USA) 53Installation of the US Skids
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Earth emits a tiny heat flux with an average value of
ΦH ~ 60 mW/m2
Integrating over the Earth surface:
HE ~ 30 TW
Giving constrain on the heat generation within the Earth.
Detecting antineutrino emitted by the
decay of radioactive isotopes
It is possible to study the radiochemical composition of the Earth
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K)of% 0.0118K( nat40
gBq40
gBq232
gBq238
30K
4000Th
12300U
K)of% 0.0118K( nat40
gBq40
gBq232
gBq238
30K
4000Th
12300U
(ε is the present natural isotopic abundance)
(11%) MeV1.51e
νAreK
(89%) MeV1.32e
νeCaK
MeV42.8e
ν44e6αPbTh
MeV51.7e
ν66e8αPbU
4040
4040
-208232
-206238
238U 232Th 40K
g
W103.6ε(K)
g
W102.7ε(Th)
g
W109.5ε(U)
21
8-
8-
Heat
sgK
sgK
sgTh
sgU
Neutrinos
e
e
e
e
e
e
e
e
3.3)(
27)(
106.1)(
104.7)(
4
4
The 235U chain contribution can be neglected
2ln2
1A
N A
g
W109.8
J
MeV101.6MeV51.7
g
Bq12300 813-
sge
e
4104.76g
Bq12300
Heat
:ratio fixeda haselement Each
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The best method to detect electron antineutrino is the classic Cowan Reines reaction of capture by proton in a liquid scintillator:
The electron antineutrino tag is made possible by a delayed coincidence of the e+ and by a 2.2 MeV γ-ray emitted by capture of the neutron on a proton after a delay of ~ 200 µs
enpe
)8.1(2)()( 2 MeVQcmQEeE ee
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238U and 232Th chains have 4 β with E > 1.8 MeV : end.point
[Th-chain] 228Ac < 2.08 MeV
[Th-chain] 212Bi < 2.25 MeV
[U-chain] 234Pa < 2.29 MeV
[U-chain] 214Bi < 3.27 MeVAnti-neutrino from 40K are under threshold!
The terrestrial antineutrino spectrum above 1.8 MeV has a “2-component” shape.
high energy component coming solely from U chain andlow energy component coming with contributions from U + Th chains
This signature allows individual assay of U and Th abundance in the Earth
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13C(α,n)16O
Reactors
Nature vol 436 july 20 2005Experimental investigation of geologicallyproduced antineutrinos with KamLAND
α’s are produced by 210Po that created by the 210Pb (τ = 22.3 y)
210Pb 210Bi 210Po
210Pb
α=5.30 MeV
KamLAND
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Borexino is located in the
Gran Sasso underground laboratory (LNGS)
in the center of Italy: 42°N 14°E
Calculated anti-νe flux at the Gran Sasso Laboratory
(106 cm-2 s-1)
U Th Total (U+Th) Reactor BKG
Crust Mantle Crust Mantle
3.3 0.95 3.0 0.77 8.0 0.39
Data from the International Nuclear
Safety Center (http://www.insc.anl.gov)
Background from nuclear
Reactors
Earth data from F. Mantovani et al., Phys. Rev. D 69 (2004) 013001
No working nuclear plants in Italy
The nearest are at about 700 km
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210Pb concentration measured in the Counting Test Facility
20 /Bq ton
Background from Po-210 13 16( , )C n O
• 210Pb related background negligible
• Only significant source of background are nuclear reactors
• Accidental rate also negligible (< 10% of reactors background)
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The number expected events in Borexino are:
The background will be:
yr
events6
yr
events19
Predicted accuracy of about 30%
in 5 years of data taking