solar and reactor neutrino experiments -...
TRANSCRIPT
Solar and Reactor Neutrino Experiments
Heraeus Seminar April 2014
Bad Honnef
L. Oberauer, TUM, Physik-Department
Content
• Solar neutrino results from Borexino • Search for sterile neutrinos with SOX/Borexino • Reactor neutrino results from Double-Chooz,
Daya-Bay, RENO • Future neutrino observatory JUNO
Neutrino reactor anomaly and future experiments are covered by talk from Christian Buck (MPIK Hd)
Status of neutrino mixing
ννν
−
−
−=
ννν
δ
δ−
τ
µ
3
2
1
1212
1212
13i
13
i1313
2323
2323
e
1000cs0sc
c0es010es0c
cs0sc0001
atmospheric ν + K2K, MINOS
Δm223= 2.4· 10-3 eV2 Θ23 ~ 42°
reactor ν DC, DB, RENO Δm2
31≈Δm2atm
Θ13~ 9 °
solar ν + KamLAND
Δm212 = 7.6· 10-5 eV2
θ12=(34±3)°
• Mass hierarchy (MH) ? ∆m231 = m2
3 – m21 > 0 or < 0 ?
• CP phase δ ?
open questions in neutrino physics: absolute mass scale, Majorana/Dirac?,...
3
Results from Solar Neutrino Experiments
The dominating solar pp - cycle
pp - 1 pp -2 pp -3
H. Bethe
W. Fowler
5
The sub-dominant solar CNO - cycle
…dominates in stars with more mass as our sun…
=>Large astrophysical relevance
⇒CNO neutrino measurement = determination of the inner solar metallicity
6
Solar Neutrino Physics
• Big success in the past • Neutrino Oscillations ! • Solar Neutrino problem solved ! ...but two questions are open Solar metallicity ? MSW effect in 8B – spectrum ?
7
Solar abundance problem • Best SSM (high-Z) and best solar atmosphere models (low-Z)
lead to contradicting results: solar abundance problem • AGSS09 does not agree with helioseismology ! • Only CNO neutrino measurement can disentangle this
problem !
8
Matter effect ?!
9
Where is the up-turn in 8B ?
Solar Neutrinos
Neutrino Energy in MeV
MeV7.2622He4 4 +++→ +eep ν
BOREXINO
10
11
BOREXINO Detector layout
Water Tank: γ and n shield µ water Č detector 208 PMTs in water 2100 m3
Carbon steel plates
Scintillator: 270 t PC+PPO in a 150 µm thick nylon vessel
Stainless Steel Sphere: 2212 PMTs +
concentrators 1350 m3
Nylon vessels: Inner: 4.25 m Outer: 5.50 m
Excellent shielding of external background
Increasing purity from outside to the central region
12
13
Data taking since May 2007 1st result on 7-Be neutrinos August 2007 High precision 7-Be measurement 8-B neutrino measurement at E > 3 MeV 1st pep-neutrino evidence Geo-neutrino detection Neutrino speed measurement
Precision measurement of solar 7Be-Neutrinos
Suppression of systematical uncertainties
Fiducial volume Detector response
14
Borexino most recent result on7-Be Neutrinos
Rate solar 7Be-neutrinos: 46 ± 1.5stat ± 1.5sys / (d 100t)
(750 days, 4.3 % total uncertainty) 15
Comparison with SNO – Test of MSW effect
16
8B- and pep-Neutrino rates
New limits on CNO-Neutrinos
17
8B-Spectrum by BOREXINO
data
MSW-LMA + high metallicity
MSW-LMA + low metallicity
Energy (MeV)
18
19
First measurement of pep-neutrinos
20
No-oscillation of pep-neutrinos excluded at 97 % cl Assuming MSW-LMA solution yields pep-neutrino flux
Is this result consistent with neutrino oscillations?
Asuming „standard solar models“ the Borexino result is in very good agreement with neutrino oscillations (plus matter effect)
21
Probing the solar MSW effect with Borexino
Borexino and search for sterile neutrinos
• Oscillometry search for sterile neutrinos search for 0νββ−decay with dissolved Xenon
22
23
Theta_13 Experiments
24
Reactor experiments Double-Chooz
Daya-Bay RENO
sin22θ13 sin22θ12
νν
∆θθ−
∆θ−≈ν→ν
4ELmsin2sincos
4ELmsin2sin1)P(
2sol2
122
134
2atm2
132
ee
CHOOZ
KamLAND
Science Week, 29.11.2011 Marianne Göger-Neff 25
Nuclear reactors are intense sources of electron antineutrinos
Average neutrino energy: <Eν>≈ 4 MeV => disappearance of νe
Clean measurement of θ13 , no dependence on δ-CP, no matter effects
Double Chooz - Site Distance: 1060 m Overburden: 300 mwe Signal: 50 ev/day
Distance: 400 m Overburden: 120 mwe Signal: 300 ev/day
France
Chooz
Pth = 2 x 4.25 GW
D. Dwyer, TAUP 2013
RENO experiment in South-Korea
prompt
delayed
Gd
µs 30 ~ MeV)8(~s'GdGdGdn
τ
γ+→→+ ∗
Antineutrino Signal
nepe +→+ν +
delayed event
Inverse Beta Decay (IBD): Qthr = Mn + me – Mp
≈ 1.8 MeV
prompt event MeV81
MeV8.0EEE nvis
−≈
−−≅ ν
157Gd, 155Gd: high cross section for n capture
( but also: n + H -> D + 2.2 MeV γ)
γ→+ −+ 2ee
Science Week, 29.11.2011 Marianne Göger-Neff 29
calibration glove box
outer muon veto: plastic scintillator strips
target: 10.3 m3 Gd-loaded scintillator 0.1%
in acrylic vessel (d=2.3m, h=2.5m)
γ-catcher: 22.4 m3 unloaded scintillator
in acrylic vesssel (d=3.4m, h=3.6m)
non-scintillating buffer: 100 m3 mineral oil
in stainless steel vessel (d=5.6m, h=5.7m)
390 PMTs (10")
inner muon veto: 90 m3 liquid scintillator
in steel vessel (d=6.6m, h=7m)
78 PMTs (8")
15 cm steel shielding (250 t)
7m
© Imag’In IRFU
Detector Design
Science Week, 29.11.2011 Marianne Göger-Neff 30
D. Dwyer, TAUP 2013
Most recent highlights
Gd+H2 combined: 0.102 +_ 0.043
Submitted to PLB (2014)
Daya-Bay spectral analysis Daya-Bay is after Double-Chooz the second experiment able to perform a spectral analysis (not only counting)
JUNO
34
Jiangmen Underground Neutrino Observatory
Measurement of neutrino oscillation parameter (MH, high precision Θ12) with reactor neutrinos
35
JUNO liquid scintillator detector (schematic view)
Yifang Wang, 27. June 2013, San Francisco
Signature: NH: RL > 0 and PV > 0 IH: RL < 0 and PV < 0 (perfect detector assumed)
Sensitivity of JUNO for wrong MH exclusion on a 3-sigma level
Dependency on resolution
Dependency on mass splitting
Dependency on Theta_13 Master thesis of Julia Sawatzki, TUM, 2014
=> this is a very important parameter to determine experimentally...
Current lab activities at TUM: - LAB purification methods
- LAB light yield response
- High purity glas for PM
production
Purified LAB
absorption
Wavelength (nm)
LAB+3g/l PPO Detemrination of non-linearities P. Hackspacher, Master-thesis J. Eckart, Bachelor-thesis
Summary • Solar Neutrinos at Borexino: high precision period started, results in agreement
with LMA & MSW-effect (range from 0.86 MeV 7Be-ν over 1.4 MeV pep-ν to 14 MeV 8B-ν) • Source experiment SOX at Borexino (search for sterile ν‘s) progressing • Discovery and consistent high precision measurement of Θ13 in the three
reactor experiments Double-Chooz, Daya-Bay, and RENO
• New project JUNO for neutrino MH and precision measurements on neutrino mixing parameter