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Сессия ЯФ ОФН РАН , 30.11.07 г. , ИТЭФ Статус экспериментальных работ по измерению магнитного момента нейтрино Старостин А.С. ИТЕФ. Science motivation of the searching for μ . minimally-extended Standard Model: μ ~ 10 – 19 B (m / 1eV) - PowerPoint PPT Presentation
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Сессия ЯФ ОФН РАН, 30.11.07
г., ИТЭФ
Статус экспериментальных работ по
измерению магнитного
момента нейтрино
Старостин А.С.
ИТЕФ
Science motivation of the searching for μ minimally-extended Standard Model:
μ ~ 10–19 B (m / 1eV)
(B = eh /2me Bohr magneton) number of extensions beyond the MSM independently of
neutrino mass:
μ ~ 10–10 - 10–12 B
limits for the NMM from astrophysics (0.4 – 0.05) 10–10 B
(model dependent !!!)
it is necessary to make laboratory measurements sensitive
enough to reach ~ 10 –11 B region and test hypotheses beyond the MSM .
Experimental measurements μ
The effects of the NMM can be searched for in the recoil electron spectrum from - e scattering.
For a non-zero NMM the differential over the kinetic energy T of the recoil electron cross section d/dT is given by
At small recoil energy in d/dT the weak part practically constant, while the EL one grows as 1/T towards low energies.
As a neutrino source in the experiments it’s used solar neutrino and reactor antineutrino. In future it’s planes to use artificial neutrino sources.
(d/dT)weak + (d/dT)EL
Солнечные нейтрино
p + p d + e+ +e (E 0,420 MeV)
p + e- + p d +e (E =1,442 MeV)
3He +p 4He+ e+ +e(18,77 MeV)
7Be + e- 7Li +e (E =0,862 MeV)
8B 7Be* + e+ +e (E 14,6 MeV)
Ф ~ 6 1010 см -2с -1
Limit for the NMM from solar data The spectrum distortion analysis of SK electron recoil spectrum can
allow to set limit of : [hep-ex/0402015]
3.6 10-10B at 90% CL – SK data alone
1.1 10-10B at 90% CL – SK + constrains from the other solar neutrino and KamLAND results (Δm2 = 6.6 10-5 eV2, tan2 θ = 0.48).
BOREXINO claim (2010)
3.0 10–11 B
The average figures for LWR:
Fuel composition→ 235U , 239Pu , 238U , 241Pu
Average energy per fission Ef = 205.3 Mev.
Number of the fiss. / sec Nf = W/ Ef = 9.14×10 19 f/s n per fiss. = 7.2 → 6.0 ( fiss. fragments) + 1.2 ( 238U n,γ 239U → 239Np → 239Pu)
0 2 4 6 81E-5
1E-4
1E-3
0,01
0,1
1
0 < E < 9 MeV
An
tin
eu
trin
o s
pe
ctr
um
, 1
/(M
eV
*fissio
n)
Energy, MeV
F = n W/E = 6.4 × 10 20 /3GWth/secAt R = 14 m f 3 × 10 13 /cm 2 sec
Reactor as a source of antineutrino
MUNU experiment
France, Switzerland, Italy NPP (2800MWth) Bugey, France CF4 TPC total mass 11.4 kg Measurements e - scattering angle
with respect to R core direction MUNU data (66.6 d ON/16.7 d OFF)
[PLB 564, 2003; hep-ex/0502037] Limits depends on energy range
taken : T > 900 keV [PLB 564, 2003]
< 1.0 10 -10 B (90% CL) T > 700 keV [ hep-ex/0502037]
< 9.0 10 -11 B (90% CL)
TEXONO experiment
Collaboration: Taiwan, China, Turkey
Kuo-Sheng PP in Taiwan. Reactor thermal power - 3 GW.
Distance from center of reactor core 28
-flux equal ~ 7×1012 / cm 2 / s
HPGe mass 1 kg enclosed by active NaI/CsI anti-Compton, further by passive shielding & cosmic veto
TEXONO result TEXONO data (197/52 days ON/OFF - 2003) [PRL 90, 2003] (571/128 days ON/OFF - 2006) [hep-ex, 0605006]
BG level at 10-20 keV : ~ 1 day-1 keV-1kg-1 (cpd)
analysis threshold 12 keV
No excess of counts ON/OFF comparison
Limit:
< 7.4 10 -11 B (90% CL)
Experiment GEMMA ((GGermanium ermanium EExperiment for measurement xperiment for measurement
of of MMagnetic agnetic MMoment of oment of AAntineutrino) ntineutrino)
ITEP – LNP JINR DubnaITEP – LNP JINR Dubna
[Phys. of At.Nucl.,70,№11(2007)1873]
Spectrometer includes a Spectrometer includes a HPGeHPGe detector of detector of 1.5 kg1.5 kg installed within installed within NaINaI active active shielding. shielding.
HPGe + NaI are surrounded with multi-HPGe + NaI are surrounded with multi-layer passive shielding layer passive shielding electrolytic electrolytic coppercopper, borated , borated polyethylenepolyethylene and and leadlead..
Circuit noises were discriminated by means method of frequency analysis of signals.
Reactor #2 of the
“Kalininskaya” Nuclear Power Plant
(400 km North from Moscow)
Technological roomjust under reactor
14.0 m14.0 m only!
Power: 3 GWON: 300300 days/yOFF: 6565 days/y
Total mass above(reactor, building, shielding, etc.):
~70 m~70 m of W.E.
0 500 1000 1500 2000 2500
1E-3
1E-2
1E-1
1E+0
1E+1
1E+2
1E+3
1E+4
1E+5
1E+6
1E+7
1E+8
êýÂ
Ñ÷åò / êý / êã / ä åí ü
Cs-137 Co-60
K-40
Cs-134
Tl-208
U-238+
Áåç çàù è òû
Óñòàí î â ë åí àï àññè â í àÿ çàù è òà
Âêë þ ÷åí ààêòè â í àÿ çàù è òà
Th-232+
EnergyADCAmp. Gedetector
ADC-1
ADC-2
E1
E2
1
2
High freq. noise: E1 > E2
Real signal: E1 = E2
Low freq. noise: E1 < E2
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
E [keV]
3..4
2
5..8
9..16
17..32
33..64
65..128
1
129..256
257..512
513..1024
1025..2048
2049..
Color LOG-scale:
E (ADC-1)
E (ADC-2)
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 êýÂ
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Pb-210
Ge-73 Pb-212Pb-214
Th-234
Xe-133
Ñ÷åò / 0.1 êý / êã / ä åí ü
Ge-68
ПослеФурье-фильтрации
4 6 8 10 12 14 16 18
1000
100
10
1
0.1
X[Ga] + 10.86% X[Zn]( Ge-68 )ðàñï àä
The sensitivity of the current experiment
4
1
1
mt
BN
NN : number of signal events expected
BB : background level in the ROI
mm : target (=detector) mass
t t : measurement time
N ~~ ( ~ Power / r 2 ) ~~ log( Tmax / Tmin )
GEMMA I 2005 – 2008
~~ 2.7 ×1013 / cm2 / s
t ~ 3 years
B ~ 2.5 keV-1 kg-1 day-1
m ~ 1.5 kg T-th ~ 3.0 keV
4 10 -11 B
Preliminary result for 2 years
(anti)neutrino magnetic moment:
µ ≤ 5.8∙10–11 µB (90% CL)
Available as (hep-ex/0705.4576, Yad. Phys.(2007) 70, p.1925)
Status : “on” 446.9 d / “off” 123.2 d – collected “on” 216 d / “off” 77.2 d - processed
GEMMA II 2009 – 2011
Distance: 14m → 10m ~ 5.4×1013 / cm2 / s t ~ 3 years B ~ 0.2 keV -1 kg -1 day-1 m ~ 6.5 kg (two detectors) T-th ~1.2 keV
GEMMA III
expected sensitivity in future experiments
1 10 –11 B
Summary
For last years general results were obtained in reactor experiments
Now best limit on NMM µ ≤ 5.8∙10–11 µB (90% CL)
The GEMMA II planes to reach sensitivity to 2011y.
µ ~ (1.0 ÷1.5) ∙10–11 µB