1. A Search of Neutrino Magnetic Moment at the Kuo-Sheng Power Plant in Taiwan
Neutrino Magnetic Moment : Overview
Kuo-Sheng(國聖) Reactor Neutrino Lab.
※ Magnetic Moments Results with ULB-HPGe
Status and Plans
Hau-Bin Li / 李浩斌
Academia Sinica
CosPa 2003, NTU Taipei

2. ne Magnetic Moment
consistent with solar neutrino data(before KamLand result)
could be reached by present lab. exp.

3. Limits of Neutrino Magnetic Moment
PDG quoted:
 Fit on SuperK data,
Reactor scattering:
 Savannah River(plastic scintillator),
 Kurtchatoc(fluorocarbon scintillator),
 Rovno(Si(Li)),
 MUNU , threshold ~ 1 MeV.
Astrophysics bound:
 in SN1987A,
 constraint at nucleosynthesis,
 red giant luminosity,
depend on stellar & neutrino mass/interaction model.

4. Measurement: Recoil energy of
ne e Scattering
Measurement: Recoil energy of

5. mn with Reactor ne mn Experimental Probe:
 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

6. ULB-HPGe + Anti-Comptons
KS Expt. : Period I Configuration
Period I : June 01 – April 02 (60 days OFF)
Shielding & Veto [one side]
ULB-HPGe + Anti-Comptons
CsI(Tl) Array (46 kg)

7. KS Expt: Period I Detectors
ULB-HPGe [1 kg]
CsI(Tl) [46 kg]
FADC Readout
[16 ch., 20 MHz, 8 bit]
Multi-Disks Array [600 Gb]

8. KS/P1/Ge/mn Data Data Volume: HPGe Performance: Analysis:
 Total 4712/1250 hours ON/OFF
HPGe Performance:
 kg mass
 0.4 keV 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

9. Cosmic Veto, Anti-Compton & PSD
Events correlated to Cosmic
No signal in Anti-Compton detectors
PSD : Events Selected

10. Efficiency & Uncertainties
Event selection
Suppression
Efficiency
Raw data
1.0
Anti-Compton (AC)
0.06
0.99
Cosmic-ray veto(CRV)
0.96
0.95
Pulse shape analysis
0.86
Combined efficiency
0.05
0.94
Sources
Uncertainties
DAQ live time ON/OFF
< 0.2%
< 0.30
Efficiencies for magnetic scattering
< 0.01
Rates for magnetic scattering
24%
0.23
SM background subtraction
23%
0.03
Combined systematic error
. . .
< 0.4

11. 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)  mB
@ 90(68)% C.L.
H.B. Li et al., TEXONO Coll., Phys. Rev. Lett. 90, (2003)

12. Reactor mn(ne) Sensitivities
Gn Sensitivities

13. Reactor Neutrino Interaction Cross-Sections
P2: SM (ne) > 2 MeV
P1: MM (ne) keV
P3+: Coh. (nN) < 1 keV

14. Calibration & Threshold of LEGe Detector
Source : Fe, Ti
60eV
Threshold : 60eV
Noise
PSD of noise and signal
Signal

15. Period II & III Summary Period II: HPGe
mn + Gn : /900 hours ON/OFF data
 improved background & analysis
Period II: CsI(Tl) [186 kg]
attempt measurement of Standard Model s(nee-)
 sin2qw at MeV range
Period III : ULE-HPGe [5 g]
threshold ~ 60 eV
explore potentials on nN coherent scattering
study quenching factor & pulse shape  neutron beam exp.