Low Energy Neutrino Physics at the Kuo-Sheng Reactor Laboratory in Taiwan
Overview of TEXONO Collaboration
Kuo-Sheng Reactor Neutrino Laboratory
Results on Neutrino Magnetic Moments
Status on Neutrino-Electron Elastic Scattering
R&D projects towards Neutrino-Nucleus Coherent Scattering
(coupled with H.Wong’s talk)
Summary
Lin,, Shin-Ted/ 林興德On Behalf of Taiwan Experiment On NeutrinO (TEXONO) Collaboration
Institute of Physics, Academia Sinica / 中央研究院@ TAUP2007,sendai Japan
TEXONO Collaboration
Collaboration : Taiwan (AS, INER, KSNPS, NTU) ;
China (IHEP, CIAE, THU, NJU) ;
Turkey (METU) ; India (BHU) ; Korea (KIMS)
Program: Low Energy Neutrino & Astroparticle Physics
Kuo-Sheng (KS) Reactor Neutrino Laboratory oscillation expts. m0 anomalous properties & interactions
reactor : high flux of low energy electron anti-neutrinos
physics full of surprises , need intense -source
※ study/constraint new regime wherever experimentally accessible
※ explore possible new detection channels
Kuo-Sheng Nuclear Power Plant
KS NPS-II : 2 cores 2.9 GW
KS Lab: 28 m from core#1
Kuo Sheng Reactor Neutrino Laboratory
Configuration: Modest yet Unique
Flexible Design: Allows different detectors conf. for different physics
Front View (cosmic veto, shielding, control room …..)
Inner Target Volume
Reactor Neutrino Spectrum
/fission
235U:3.4 238U:0.5 239Pu:1.8 241Pu:0.4 U (n,) 1.2
e) ~ 6.4X1012 / sec*cm2
Reactor Operation Data
R&D : Coh. (N)
T < 1 keV
Results on (e) @T ~ 1-100 keV
ddT)>> (ddT)SM
T<<E ddT ∝ 1/T
T << E ddT depends on total flux but NOT spectral shape
On-Going Data Taking & Analysis SM (e)
T > 3 MeV
Reactor Neutrino Interaction Cross-Sections
massquality Detector requirements
22
11)(2
ETmedT
de
KS Experiment: Period I, II, III,IV,V Detectors
FADC Readout
[16 ch., 20 MHz, 8 bit]
ULB-HPGe [1 kg] CsI(Tl) Array
Multi-Disks Array [few Tbs]
8
Neutrino Electromagnetic Properties : Magnetic Moments
• fundamental neutrino properties & interaction ; necessary consequences of neutrino masses/ mixings
• Astrophysics bound on
10-10 – 10-12 Bhowever, model dependence
• Study of anomalous e scattering is valid for
- both Dirac/Majorana - both Diagonal/Transition i j
Minimally Extended Standard Model:
However, many models can enhance it
significantly (M, WR …..)
Magnetic Moment Searches @ KS
simple compact all-solid design : HPGe (mass 1 kg) enclosed by active NaI/CsI anti-Compton, further by passive shielding & cosmic veto
selection: single-event after cosmic-veto, anti-Comp., PSD
Data Analysis
TEXONO data
(570.7/127.8 days of Reactor On/OFF)
background comparable to underground CDM experiment : ~ 1 day-1keV-1kg-1 (cpd)
DAQ threshold 5 keV analysis threshold 12 keV
Combined all information
i / f i / f Before/After cuts
Spectrum ;
SM
Reactor On/Off
e (SM) e2 e
+/ -
i
f
i
f
ff
11
• Systematic effects
• Best-fit
The limit based on 570.7/127.8 days of Reactor ON/OFF: e) <7.4 X 10-11 B (90% CL) @ PRD 75 2007
Results on neutrino magnetic moment
e (SM) e2 ee X10 -1
0 B
e2 = ±0.59 0.53 ־ (stat.) ± 0.18(sys.)
Search of at low threshold high signal rate & robustness:
Gemma prelim. Result:
e) <5.4 X 10-11 B (90% CL) @hep-ex0705.4576v1
22
11)(2
ETmedT
de
Neutrino radiative decay
13
ee scattering
However, SM >>MM at few MeV ! The differential cross section can be represented
SM MM
CsI(Tl) Array (~200 kg) : e)
Z =40 cm
Single Crystal QL Vs QR
(Raw Data)
Region of Interest for SM e)
Z = 0 cm
208Tl
40K 137Cs
Data analysis under way ..
(40000/12000 day-kg for ON/OFF in PII to PV)
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Status of neutrino-electron scattering
Background understanding
and suppression
--Multiple-hit analysis (Cosmic ray tagged, cascades of 208Th )
=> sin2w @6900/2300day*kg of reactor ON/OFF
X 3 data
Global analysis of all spectra
Expect:
a fundamental neutrino interaction never been experimentally-observed ; a test of standard model (T. Rashba’s talk)
an important interaction/energy loss channel in astrophysics media
R&D on an ULEGe towards (kg-scale ; 100eV threshold ; 1cpd) experiment : allow for CDM search ( H.Wong’s talk) & improve the neutrino magnetic moment [ search ~10-11 B ]
Neutrino-Nucleus Coherent Scattering
17
Kuo-Sheng Neutrino Lab.: Modular & Flexible Design Physics Data Taking since 2001 ※ Unique HPGe Low Energy Data ※ Bkg Level ~ Underground CDM Expment
Results published on (PRL 03;PRD 07)& reactor e (PRD 05) and axion ( PRD 07 HM Chang’stalk )
Diversified Program in Parallel
Main Thrust on ~200 kg CsI(Tl) [(e) …]
ULEGe: for coh(N) + CDM (H.Wong’s talk)
Summary & Outlook
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