1 / 20

Science motivation of the searching for μ 

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)

nishan
Télécharger la présentation

Science motivation of the searching for μ 

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Сессия ЯФ ОФН РАН, 30.11.07 г., ИТЭФСтатус экспериментальных работ по измерению магнитного момента нейтриноСтаростин А.С. ИТЕФ

  2. Science motivation of the searching for μ • minimally-extended Standard Model: μ ~ 10–19B (m / 1eV) (B= eh /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 measurementssensitiveenough to reach ~10 –11B region and test hypotheses beyond the MSM .

  3. Experimental measurementsμ • 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

  4. 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

  5. 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 10-10B at 90% CL – SK data alone  1.1 10-10B at 90% CL – SK + constrains from the other solar neutrino and KamLAND results (Δm2 = 6.6 10-5 eV2, tan2θ = 0.48). BOREXINO claim (2010)  3.0  10–11B

  6. Reactor as a source of antineutrino The average figures for LWR: Fuel composition→ 235U , 239Pu , 238U , 241Pu Average energy per fission Ef= 205.3 Mev. Number of the fiss. / secNf = W/ Ef = 9.14×10 19 f/s nper fiss. = 7.2 → 6.0 ( fiss. fragments) + 1.2 ( 238U n,γ239U → 239Np → 239Pu) • F= nW/E = 6.4 × 10 20/3GWth/sec • At R = 14 m f  3 × 1013 /cm 2 sec

  7. 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)

  8. 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

  9. 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 excessof counts ON/OFF comparison • Limit: < 7.4  10 -11B(90% CL)

  10. ExperimentGEMMA (Germanium Experiment for measurement of Magnetic Moment of Antineutrino) ITEP – LNP JINR Dubna [Phys. of At.Nucl.,70,№11(2007)1873] • Spectrometer includes a HPGe detector of 1.5 kg installed within NaI active shielding. • HPGe + NaI are surrounded with multi-layer passive shielding  electrolytic copper, borated polyethylene and lead. • Circuit noises were discriminated by means method of frequency analysis of signals.

  11. Reactor #2 of the “Kalininskaya” Nuclear Power Plant (400 km North from Moscow) Power: 3 GW ON: 300 days/y OFF: 65 days/y Total mass above (reactor, building, shielding, etc.): ~70 m of W.E. Technological room just under reactor 14.0 m only!

  12. High freq. noise: E1 > E2 Real signal: E1 = E2 Low freq. noise: E1 < E2

  13. E (ADC-2) E (ADC-1)

  14. После Фурье-фильтрации

  15. The sensitivity of the current experiment N: number of signal events expected B : background level in the ROI m : target (=detector) mass 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

  16. Preliminary result for 2 years Status: “on” 446.9 d / “off” 123.2 d – collected “on” 216 d / “off” 77.2 d - processed • (anti)neutrino magnetic moment: µ≤ 5.8∙10–11 µB(90% CL) Available as(hep-ex/0705.4576, Yad. Phys.(2007) 70, p.1925)

  17. expected sensitivity in future experiments 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 ~1.2keV GEMMA III  1  10–11 B

  18. 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

More Related