A Search of Neutrino Magnetic Moment at the Kuo-Sheng
Power Plant in Taiwan
 TEXONO Collaboration : Overview
 Kuo-Sheng Reactor Neutrino Lab.
※ Magnetic Moments Results with ULB-HPGe
 Other Physics, Status and Plans
Hau-Bin Li
Academia Sinica
EPS03, Aachen
Program:
TEXONO Overview
Kuo-Sheng Reactor Neutrino Laboratory
※ reactor : high flux of low energy electron anti-neutrinos
※ mn0  anomalous n properties & interactions
※ n physics full of surprises
 study/constraint new regime wherever possible experimentally
 explore possible new detection channels
 R&D Projects
Achieved :
 KS Expt: 1st particle physics experiment in Taiwan
 TEXONO Coll. : 1st big research Coll. % Taiwan & China
[feature report in Science, Vol. 300, 1074 (2003) ]
Kuo-Sheng Nuclear Power Plant
KS NPS-II :
2 cores  2.9 GW
KS n Lab:
28 m from
core#1
Kuo Sheng Reactor Neutrino Laboratory
Front Gate
Front View (cosmic vetos,
shieldings, control room …..)
Configuration: Modest yet Unique
Flexible Design: Allows different
detectors conf. for different physics
Inner Target Volume
KS Expt. : Period I Configuration
Period I : June 01 – April 02 (60 days OFF)
Shielding & Veto [one side]
ULB-HPGe + AntiComptons
CsI(Tl) Array (46 kg)
KS Expt: Period I Detectors
ULB-HPGe [1 kg]
FADC Readout
[16 ch., 20 MHz, 8 bit]
CsI(Tl) [46 kg]
Multi-Disks Array [600 Gb]
mn with Reactor ne
 mn
 parametrize possible niL njR + g vertices
  both i = j “diagonal” & i  j “transition” moments
 Experimental Probe:
 Study ne + e-  nX + e Focus on low recoil energy
※ sm  T–1
※ decouples SM “background”
[ ……… LE reactor f(ne) not accurately known]
 Look for Excess in Reactor ON/OFF
 Neutrino Radiative Decay (Gn):
 sm & Gn related:
 same vertices – real g for Gn
Electron Recoil Spectra
KS/P1/Ge/mn Data
 Data Volume:
 Total 4712/1250 hours ON/OFF
 HPGe Performance:




1.06 kg mass
0.4 keV RMS @ 10 keV
5 keV detector threshold [Unique Data]
Range of O(1 cpd) [counts kg-1 day-1 keV-1]
background c/f Dark Matter expt.
 Analysis:
 Cosmic Veto (5 ms gate)
 Anti-Compton (Well+Base detectors)
 Pulse Shape Disc. (veto elect. noise, accidentals)
 Efficiencies Normalization: (to <0.2%)




DAQ book-keeping
Monitor random triggers
Monitor residual 40K peaks
Monitor 10 keV Ga X-rays peak
Cosmic Veto, Anti-Compton & PSD
Events correlated to Cosmic
No signal in Anti-Compton detectors
PSD : Events Selected
KS/P1/Ge/mn : Results
 Fit OFF spectra to p5
Measure [fOFF;dfOFF ]
(@ c2/dof = 80/96 )
 Fit ON spectra to
fOFF + fSM + k2 fMM [10-10 mB]
Fit Results (@ c2/dof = 48/49 ):
k2 = -0.4  1.3 (stat.)  0.4 (sys.)
Limits derived :
mn < 1.3 (1.0)  10-10 mB
@ 90(68)% C.L.
H.B. Li et al., TEXONO Coll., Phys. Rev. Lett. 90, 131802 (2003)
Reactor mn(ne) Sensitivities
Gn Sensitivities
Status & Plans
HPGe [1 kg] :
 mn + Gn : x2 more data
improved background & analysis
 study ne flux from reactor
 study possible nuclear transitions
e.g. 73Ge* decays by 2g’s separated by t1/2=4.6 ms
CsI(Tl) [186 kg] :
 attempt measurement of Standard Model s(nee-)
 sin2qw at MeV range
Prototype ULE-HPGe [5 g] :
 threshold < 300 eV
 explore potentials on nN coherent scattering
Reactor Neutrino Interaction Cross-Sections
P2: SM
(ne) > 2
MeV
P1:
P3+: Coh.
MM (ne)
(nN) <
1-100 keV
1 keV
Summary
 TEXONO Collaboration:
 Built-Up and Growing
 Kuo-Sheng Neutrino Lab.:
 Established & Operational
※Modular & Flexible Design
 Physics Data Taking since June 01
※Unique HPGe Low Energy Data
※ Bkg Level ~ Underground CDM Expt.
 Results published on mn (Gn)
※ Other analyses under way
 Period-II DAQ
 Improved HPGe Conf.
 186 kg CsI(Tl) [+ s(ne) …]
 Diversified R&D Program in parallel