1. Research Program of TEXONO Collaboration on Neutrino & Astroparticle Physics
Overview
Kuo-Sheng Period I Program
 Results on Neutrino Magnetic Moment
Period II Data Taking & Focus
R & D Program
Henry T. Wong / 王子敬
Academia Sinica / 中央研究院
@ 2nd NCTS Workshop on Astropart. Phys.
January 2003

2. Experimental Neutrino Physics ……

3. 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, 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, Y.H. Liu, 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, D.Z. Liu
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
*Taiwan EXperiement On NeutrinO
Home
HISTORY
Initiate : Chang Chung-Yung 1996
First Collab. 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.
First Physics Result : December 2002

4. 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
Kuo-Sheng Reactor Neutrino Lab.
※ reactor : high flux of low energy electron anti-neutrinos
※ mn0  anomalous n properties & interactions
※ n’s strange & full of surprises
 study/constraint new regime wherever possible experimentally
R&D Projects
 diversified program ※ reactor program as base
※ explore various future scenarios
Program:

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

6. 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

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

8. 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)

9. 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]

10. 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

11. PDG Limit : 1.5 X mB
(from SK spectral shape)
an allowed solution for the solar neutrino data (before KamLAND)

12. KS/P1/Ge/mn Data Data Volume: HPGe Performance: Analysis:
 Total Live Time 196/52 days 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, accidentals)
Efficiencies Normalization: (to <0.3%)
 DAQ book-keeping
 Monitor random triggers
 Monitor residual 40K peaks
 Monitor 10 keV Ga X-rays peak

13. Kuo Sheng Reactor Neutrino Experiment : First Results

14. KS/P1/Ge : Spectra & Residual
Based on 196/52 days of Reactor ON/OFF data
No anomalous structures or residuals

15. KS/P1/Ge/mn : Results Fit OFF spectra to fOFF Fit ON spectra to
E/keV fOFF c2/dof
12-61 p /96
Fit ON spectra to
fOFF + fSM + k2 fMM [10-10 mB]
[using best-fit values of (fOFF;dfOFF)]
Fit Results c2/dof = 48/49 ):
k2 = -0.5  1.4 (stat.)  0.3 (sys.)
Limits derived :
mn < 1.3 (1.0) X mB @ 90(68)% C.L.
Improvement in Period 2:
 4p anti-Compton coverage
 improved inner shielding
 Aim of analysis threshold: ~ 5 keV
 study “ultra-low” energy Ge prototype [threshold : eV]
Residual Plot

16. Reactor mn(ne) Sensitivities
Gn Sensitivities

17. 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

18. Reactor as ne Source Fission Material Fission Products Neutrons
odd-odd nuclei
Structural materials of reactor
Electron capture or + decay ( neglected )
νe Emission
Captured
Mostly rich in neutrons
¯ Decay back to  stable valley
Anti-neutrino Emisson

19. Simulation Result
51Cr + e-  51V + νe
55Fe + e-  55Mn + νe
59Ni + e-  59Co + νe
Model of Reactor Core
Simulated neutrino emission Spectrum
Total neutrino emission rate normalized to per fission is: ~0.075
Correspond to an emission rate of 6 νe per fission on the energy range of < 1MeV : ~ 10-2

20. 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

21. Search for Anomalous dE/dx
Measure “DC” leakage
current in HPGe
Energy Quanta:
5 keV > X > 2 eV
Expect sensensitivities:
dE/dx[n+matter] ~ dE/dx[m.i.p]

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

23. 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 46 kg target
Goals:
Operate 186 kg target on-site
for Period-2
DAQ with large dynamic range

24. Period-2 CsI(Tl) Array : 186 kg, 93 crystals
Single Crystal QL Vs QR
137 Cs
40 K

25. KS/P2:
93-Element
CsI(Tl) Array
(to be optimized)

26. 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 [ observe SM + test exotic processes….]
Insert passive targets for s(nucl.) e.g. 6Li, 7Li, 10B, 11B,2H ..
 s(NC) related to axial isoscalar &
strange quark structure in nucleon
As base to launch other projects
 explored by R&D program

27. R&D Projects Upgrading FADCs
Explore New Detectors Scenarios
 loaded crystal scintillator (GSO, YbAG, LSO …..)
 ultra low energy HPGe [ O(100 eV) threshold ]
CsI(Tl) for Dark Matter Searches
Upgrading FADCs
Trace Radio-purity with AMS ( Accelerator Mass Spectrometry)
Sono-Luminescence Project (fermenting ……..)
Close Contact with :  CsI(Tl) CDM Korea
 JHFBeijing LBL n IHEP
 Ultra HE (1015 eV) n NTU

28. 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-calor. 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. & Max. Likelihood
 improve conventional methods
N KIMS Expt. (apprd.) :
 kg CsI(Tl) for CDM
in S. Korea

29. TEXONO/KS FADC for SPring8
40 MHz ; 12 bit ; 32 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 SPring8 by End 2002.
TPC for SPring8
Mixed signal FADC Adapter Board
40 MHz sampling rate.
10 bits resolution with 2Vp-p dynamic range.
Clock distribution with Phase Lock Loop circuit.
On Board digital signal delay and
Real-Time ZERO-Suppression.
High capacity First In First Out Memory.
Easy to use with high density connector.
Prototype Measurements :
(cosmic muon)

30. 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]

31. Status: TEXONO Collaboration: Kuo-Sheng Neutrino Lab.:
 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.
Expect Results on mn (Gn) soon
※ Other speculative analyses under way
Period-2 DAQ
 Improved HPGe Conf.
 Commissioning 186 kg CsI(Tl) [+ s(ne) …]
Diversified R&D Program in parallel

32. Summary & Outlook Neutrinos are important but strange objects
history of n physics full of surprises !
Strong evidenceS of massive n’s & finite mixings
Physics Beyond the Standard Model !
More experiments & projects coming up
EVEN MORE EXCITEMENT !
TEXONO is also a (modest) part of it
Tremendous Pleasure & Pressure !