1. Research Program of TEXONO : Status and First Results
TEXONO Collaboration : Overview
Kuo-Sheng(國聖) Reactor Neutrino Lab.
※ First Results with ULB-HPGe
R&D Projects
Status and Plans
Henry T. Wong / 王子敬
Academia Sinica / 中央研究院
@ Matsushima, Sendai / 仙台 松島
March 02

2. TEXONO* Collaboration
W.C. Chang¶, C.P. Chen, K.C. Cheng, H.C. Hsu, F.S. Lee, S.C. Lee, S.T. Lin,
D.S. Su, P.K. Teng, W.S. Tse¶, H.T.K. Wong†, C.S. Wu, S.C. Wu
Academia Sinica, Taipei, Taiwan
W.P. Lai
Chung Kuo Institute of Technology, Taipei, Taiwan
C.H. Hu, J.M. Huang, W.S. Kuo, T.R. Yeh
Institute of Nuclear Energy Research, Lungtan, Taiwan
H.B. Li, C.H. Tang, M.Z. Wang¶
National Taiwan University, Taipei, Taiwan
J.H. Chao, J.H. Liang
National Tsing Hua University, Hsinchu, Taiwan
Z.M. Fang, R.F. Su
Nuclear Power Station II, Kuosheng, Taiwan
M. He, S. Jiang, L. Hou, H.Q. Tang, B. Xin, Z.Y. Zhou¶
Institute of Atomic Energy, Beijing, China
J. Li†, Y. Liu, Z.P. Mao, J. Nie, J.F. Qiu, H.Y. Sheng, P.L. Wang, X.W. Wang,
Q. Yue, D.X. Zhao, J.W. Zhao, P.P. Zhao, S.Q. Zhao, B.A. Zhuang
Institute of High Energy Physics, Beijing, China
Z.S. Liu, Z.Y. Zhang
Institute of Radiation Protection, Taiyuan, China
T.Y. Chen
Nanjing University, Nanjing, China
J.P. Cheng
Tsing Hua University, Beijing, China
C.Y. Chang, G.C.C. Chang†
University of Maryland, Maryland, U.S.A.
† Co-Prinicipal Investigators
¶ Project Leaders
Ph.D. Students
HISTORY
Initiate : Chang Chung-Yung 1996
First ICollaboration Meeting/Official Start : October 1997
First Paper : October 1998
KS Reactor Experiment Installation : June 2000
First Ph.D. : Liu Yan , July 2000
First Physics Data Taking : June 2001.
*Taiwan EXperiement On NeutrinO
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3. TEXONO Overview Goals : Program : Neutrino and Astroparticle Physics
 Starting phase: 1st particle physics expt in Taiwan
Build up a Qualified Group
 1st big research Coll. % Taiwan & China
Program :
Kuo-Sheng Reactor Neutrino Lab.
※ mn0  anomalous n properties & interactions
※ n’s strange & full of surprises
 study new regime wherever possible experimentally
R&D Projects
 diversified program
※ reactor program as base
※ explore various future scenarios0

4. Kuo-Sheng Nuclear Power Plant
KS NPS-II :
2 cores X 2.9 GW
KS n Lab:
28 m from
core#1

5. Kuo-Sheng Neutrino Laboratory
High flux of ne (also ….. ne )
Modular Design
 independent detector, electronics, shielding
high-Z target, large re
Improved detector performance:
 good energy & spatial resolution,
 low threshold, a/g separation
Elaborate electronics+DAQ+control sys.
 complete record of pulse shape + timing info.
Elaborate Shieldings
 radon purge & 4p cosmic veto
Configuration: Modest yet Unique
Flexible Design: Allows different detectors conf.
for different physics

6. Kuo Sheng Reactor Neutrino Laboratory
Front Gate
Front View
(cosmic vetos,
shieldings,
control room …..)
Inner Target Volume

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

8. 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]

9. 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

10. KS/P1/Ge/mn Data Data Volume: HPGe Performance: Analysis:
 Expected total 200/60 days ON/OFF
[ reported here : 62/46 ON/OFF ]
HPGe Performance:
 kg mass
 0.4 keV 10 keV
 5 keV 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)
 Timing Analysis (veto clusters)
[not yet implemented here]
Efficiencies Normalization:
 DAQ book-keeping
 Monitor random triggers
 Monitor residual 40K peaks
 Monitor 10 keV Ga X-rays peak

11. Cosmic Veto : Timing Plot
evidence of delayed
induced neutron
activities
choose Dt=5 ms
HPGe Vs NaI(Tl) : 2D Plot
Necessary Cross Checks observed :
※ full capture peaks,
Compton edges,
coincidences …. etc

12. KS/P1/Ge : Spectra & Residual
Based on 62/46 days of Reactor ON/OFF data

13. KS/P1/Ge : First Results
Residual Plot
Fit OFF spectra to fOFF
E/keV fOFF c2/dof
a1e-a2E+a3+a4E 39/46
Fit ON spectra to
fOFF + fSM + mn2 fMM [10-10 mB]
Best Fit :
mn2 = -1.7  @ c2/dof = 55/49
[Comparable sensitivities to direct-search world limits]
Improvements Expected :
 more data [ 3+ ON]
 complete & improved analysis
 treatment of threshold region [e.g. timing]
[Aim : ~ 5 keV]

14. Reactor mn(ne) Sensitivities
Gn Sensitivities

15. KS/P1 Analysis HPGe : exploit the low threshold data
Established Problem:
mn and Gn for ne via
ne + e  nx + e
Speculative Analysis:
※ study ne flux from reactor
 due to neutron excitation producing
e.g. 51Cr, 55Fe [distinct energy & timing …..]
 study mn & Gn for ne
※ anomalous Neutrino Interactions in Matter
e.g. anomalous energy deposition X (>eV)
ne + N  nx + N + X
[similar analysis as accelerator nm]
※ study possible nuclear transitions
e.g. 73Ge* decays by 2g’s separated by t1/2=4.6 ms
CsI(Tl) : Technical Run
Event Reconstruction
Background Studies
Optimize for P2

16. 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

17. CsI(Tl) Array : Highlights
40 cm length
(longest commercial prod.)
Energy+3D info:
 10% FWHM at 660 keV
 s(z) <2 cm @ E>250 keV
Detector Threshold ~ 20 keV
PSD for g/a : > 99%
Intrinsic Purity :
 238U/232Th < g/g (equil.)
 40K < g/g
cosmic muon
events on-site
@ 46 kg target
Goals:
Commission 150+ kg target on-site for Period-II
DAQ with large dynamic range

18. KS Expt.: Future Thoughts
Existing configurations:
 push mn/Gn sensitivities
 s(ne–e) scatterings
 analysis opened up by low threshold
Push threshold lower ( X 1/10 )
 coherent nN scattering
Insert passive targets for s(nucl.)
e.g. 6Li, 7Li, 10B, 11B, 2H …..
As base to launch other projects
 explored by R&D program

19. R&D Projects Upgrading FADCs Trace Radio-purity with AMS
Explore New Detectors Scenarios
 loaded crystal scintillator
 ultra low energy HPGe
CsI(Tl) for Dark Matter Searches
Upgrading FADCs
Trace Radio-purity with AMS
( Accelerator Mass Spectrometry)
Close Contact with :
 CsI(Tl) CDM Korea
 JHFBeijing LBL n IHEP
 Ultra HE (1015 eV) n NTU

20. CsI(Tl) for CDM Searches
Potential Merits:
Better PSD for g/a separation
than NaI(Tl)
Minimal passive materials
Large target mass possible
(c/f em-calorimeters 40 tons)
Highlights of R&D Program:
Quenching Factor measurements
with neutron beam
 lowest threshold data
1st direct measurement of
diff. cross section in heavy nuclei
PSD studies with Neural Net.
 improve conventional methods
N KIMS Expt. (apprd.) :
 kg CsI(Tl) for CDM
in S. Korea

21. Upgrade FADC 40 MHz ; 12 bit ; 32 ch/module @ 9 U VME
[ c/f KS FADC : 20 MHz ; 8 bit ; 16 ch/module ]
On-board processing with FPGA
1000 channels to be used in TPC in LEPS Expt.
@ SPring8 by Fall 2002.
TPC for SPring8
Prototype Measurements :

22. Trace Radio-purity with AMS
Based at AMS
with 13 MV Tandem
Potential Merits:
 small samples, quick
 versatile on sample choice
 sensitive to a/b emitters
 sensitive to stable isotope & extrapolate (e.g. 39K)
 >103 improvements over ICP-MS
[ …….. once prescriptions are known. ]
Status :
 demonstrate 129I/127I < g/g
 measure 40K~10-10 g/g in CsI (powder)
Sensitivity goal : g/g
Future :
 different bases e.g. liquid scintillator
 87Rb ……
[238U / 232Th series after Tandem upgrade]

23. 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 ~ Udrgd. CDM Expt.
Expect Results on mn (Gn) soon
Preparation of Period-II DAQ
 Improved HPGe Conf.
 Commissioning 150+ kg CsI(Tl)
[Welcome Ideas/Suggestions on Possibilities Beyond]
Diversified R&D Program in parallel