1. Recent Result and Status of TEXONO Experiments
V. Singh (On behalf of the TEXONO Collaboration) IoP, Academia Sinica, Taipei, Taiwan
TEXONO Collaboration : Overview
Kuo-Sheng(國聖) Reactor Neutrino Lab.
※ Magnetic Moments Results with ULB-HPGe
※ Other topics being pursued/in preparation
R&D Program

2. Program: Pioneering Efforts : 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 , need intense n-source
 study/constraint new regime wherever possible experimentally
 explore possible new detection channels
R&D Projects
Pioneering Efforts :
KS Expt: 1st particle physics experiment in Taiwan
TEXONO Coll. : 1st big research Coll. % Taiwan & China
[feature report in Science, Vol. 300, 1074 (2003) ]

3. Kuo-Sheng Nuclear Power Plant
KS NPS-II : 2 cores  2.9 GW
KS n Lab: 28 m from core#1
Powerful collaboration: Scientists from Taiwan and mainland China are studying neutrinos from this nuclear power plant outside Taipei.

4. 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

5. KS Expt. : Period I Configuration
Period I : June 2001 – April 2002 (60 days OFF)
Shielding & Veto [one side]
ULB-HPGe + Anti-Comptons
CsI(Tl) Array (46 kg)

6. KS Expt: Period I Detectors
ULB-HPGe [1 kg]
CsI(Tl) [46 kg]
FADC Readout [16 ch., 20 MHz, 8 bit]
Multi-Disks Array [800 Gb]

7. 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

8. KS/P1/Ge/mn Data Data Volume: HPGe Performance: Analysis:
 Total 4712/1250 hours ON/OFF (No residual observed)
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. 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)

10. Reactor mn(ne) Sensitivities
Gn Sensitivities

11. Prototype ULE-HPGe [5 g] :
Status & Plans
HPGe [1 kg] :
mn + Gn : x2 more data
improved background & analysis
study ne flux from reactor
dominated by 51Cr : ~ (prelim.)
study possible neutrino induced 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  ~ 100 eV
explore potentials on nN coherent scattering & CDM

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

13. Tagging of 73Ge ½- 2g transitions:
Event-by-Event background-free tag with PSD
To do : Reactor ON/OFF analysis on the system ~1 s before the transition
To look for : possible n-induced nuclear transitions

14. Period-2 CsI(Tl) Array : 186 kg, 93 crystals
Single Crystal QL Vs QR (Raw Data)
Z = 0 cm
Z =40 cm
208Tl
40K
137Cs
Region of Interest for SM s(ne)

15. Data Analysis Techniques
No Cut: Energy Spectrum
Defining Cuts:
1] General Cuts – a) No Cut energy spectrum b) Single Event Hit & Single Crystal Hit c) Cosmic ray Cut
d) Rough Z-pos. cut
SEH, SCH
SEH, & SCH
SEH, SCH, & Cosmic
SEH, SCH, Cosmic-ray, & Z-pos
SEH, SCH
SEH, SCH
SEH, SCH

16. Data Analysis Techniques
Normal Event Pulse
Alpha Event Pulse
Defining Cuts: 2] Special Cuts –
a) Alpha Event Cut (having fast decay time)
Check- Alphas are located around 2 MeV
Select- event having Time average less than 40
A; .

17. Data Analysis Techniques
Defining Cuts: 2] Special Cuts –
c) Right side Double Pulse Cut
Select – Event having Larger Time Avg. but low charge ! A;
Right side Double Pulse

18. Period-2 CsI(Tl) Array : 186 kg, 93 crystals
Energy Spectrum of recoil electron
137Cs (661 keV)
40K (1461 keV)
208Tl (2615 keV)
2.9 MeV
* Central Crystal
* Mass 2 kg
* Data set 6.7 days OFF period

19. Period-2 CsI(Tl) Array : 186 kg, 93 crystals
Integrated Event Count for CsI(Tl)
* Above 3 Mev counts/day/kg
* Signal to background ration i.e., ~ 1/17 above 3 MeV
NOT bad !
* Above 3.5 MeV
NO counts !
* Further ON / OFF
Preliminary
2.9 MeV

20. “Ultra-Low-Energy” HPGe Prototype
mass 5 g ; can be constructed in multi-array form
55Fe+Ti back-scattered Spectra : noise edge at 200 eV
threshold <100 eV after modest PSD
background measurement on-site Oct 03
study appl. in nN coherent scattering and Dark Matter searches
PSD Cut
Threshold ~ 200 eV
Signal Band
Threshold < 100 eV

21. R&D Projects Upgrading FADCs (+ FPGA etc. capabilities…..)
Explore New Detectors Scenarios (LEn, CDM …)
 loaded crystal scintillator (GSO, YbAG, LSO …..)
 ultra low energy HPGe [ O(100 eV) threshold ]
CsI(Tl) for Dark Matter Searches
 CsI(Tl) CDM Korea by KIMS Coll.
Upgrading FADCs (+ FPGA etc. capabilities…..)
 for SPring8
Trace Radio-purity with AMS ( Accelerator Mass Spectrometry)
 1st goal : sensitivity of g/g in 40K
Sono-Luminescence Project (inter-disciplinary)

22. Also ………. Road tunnel at 2 km 100 m rock overburden
Geographically possible for medium baseline experiment :
Easy reach from city
Access to Plant established
Road tunnel at 2 km
100 m rock overburden

23. Summary & Outlook 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) …]
 study potentials for scoh(nN) ……
Diversified R&D Program in parallel