1. Low-Energy Neutrino and Dark Matter Physics with TEXONO Program
Overview (Collaboration; Laboratory; Program)
Highlights: Physics & Detector & Results
New Underground Laboratory at Sichuan
Status & Plans
Heng-Ye Liao/廖恒毅 On Behalf of TEXONO-CDEX Collaboration
Ph.D. Max-Planck-Institut für Physik ,
14th November , 2011

2. TEXONO + CDEX Collaboration
TEXONO: [since 1997]
Neutrino Physics at Kuo-Sheng (KS) Reactor Neutrino Laboratory
Taiwan (AS, INER, KSNPS, NTU, NTHU)
+ Turkey (METU&KTU)
+ India (BHU)
CDEX: [birth 2009]
Dark Matter Searches at China Jin-Ping Underground Laboratory (CJPL)
China (THU, SUC,IHEP, CIAE, NKU,EDHC)
Research Program : Low Energy Neutrino and Dark Matter Physics
Taiwan EXperiment On NeutrinO
China Dark Matter EXperiment
INER: Institute of Nuclear Energy Research
KSNPS: Kuo-Sheng Nuclear Power Station
METU: Middle East Technical University
KTU:Kiradeniz Techanical U.
BHU: Banaras Hindu University
INEP: Institude of High Energy Physics Chinese Academy of Sciences
CIAE: China Institute of Atomic Energy
SUC:四川U
EDHC:二灘(ERTAN) Hydropower development company

3. Kuo-Sheng Reactor Neutrino Laboratory
2.9 GW each core
28 m from core #1
Shallow site:
~ 30 m.w.e overburden
~ 10 m below ground level
Total flux:
~ 6.4x1012 cm-2s-1 #1 #2

4. Front View (cosmic vetos, shieldings, control room …..)
Inner Target Volume
Front View (cosmic vetos, shieldings, control room …..)
Flexible Design:
Allows different detectors conf. for different physics

5. Neutrino Properties & Interactions at Reactor
mass
quality
Detector requirements
Threshold ~ 100 eV
1 counts / kg-keV-day
Standard Model ne Scattering (2  PRD10)
Magnetic moments: magnetic moment can allow flavor free (flavor可以改變,left,right也可以透過magnetic moment改變)
“可”改變(i.e.可改可不改),但是我們不知道final state是什麼.
nN Coherent Scattering
Dark Matter Searches (PRD-RC09)
Magnetic Moments (PRL03,PRD07)

6. Results of νe scattering(PRD 81, 072001 2010)
Neutrino Magnetic KSNL (PRL03, PRD07) &
Results of νe scattering(PRD 81, )
The limit based on 570.7/127.8
days of Reactor ON/OFF:
μν(νe) <7.4 X μB (90% CL) (Best result in PDG 2008)
Data Volume: ~ 29883/7369 kg-day
Reactor ON/OFF
simple compact all-solid design : HPGe (mass 1 kg) enclosed by active NaI/CsI anti-Compton, further by passive shielding & cosmic veto
selection: single-event after cosmic-veto, anti-Comp., PSD
TEXONO data
background comparable to underground CDM experiment : ~ 1 day-1keV-1kg-1 (cpkkd)
DAQ threshold : 5 keV
analysis threshold : 12 keV
(Experimental studies on the neutrino properties and interactions which may reveal some of these fundamental questions and/or constrain certain classes of models are therefore of interests. The coupling of neutrino with the photons are consequences of non-zero neutrino masses. Two of the manifestations of the finite electromagnetic form factors for neutrino interactions [6, 7]
are neutrino magnetic moments and radiative decays. )
The experimental observable is the kinetic energy of the recoil electrons(T). The differential cross section for the magnetic scattering (MS) channel can be parametrized by the neutrino magnetic moment (µl), often expressed in units of the Bohr magneton(µB). Its
dependence on neutrino energy Eν is given by [6]:
ON-BKG

7. Research Theme: “sub-keV” Ge Detectors
 Physics Goals for O[100 eV threhold1 kg mass1 cpkkd] detector :
νN coherent scattering
Low-mass WIMP searches
Improve sensitivities on neutrino magnetic moments
Implications on reactor operation monitoring
Open new detector window & detection channel available for surprises

8. China Jin-Ping Underground Laboratory (CJPL)
中國四川錦屏
2500+ m rock overburden, drive-in road tunnel access
6X6X40 m cavern has built [THU & EDHC]
DM-Search: 20 g ULEGe 2010 ; 1000 g PCGe 2011
DUSEL 4850
DUSEL 7400
CJPL

9. ~2400 m
~9000 m
6 m (H) X 6 m (W) X 40 m (L)
Physics Today September 2010
CDEX-TEXONO
PandaX

10. Data Taking in CJPL –since Feb 2011
1kg PCGe
4x5g ULEGe
THU-EDHC MoU 2009/5/8
Inside with shielding structure

11. TEXONO : ULEGe & PCGe @ KSNL & CJPL
4X5g ULEGe
500g PCGe
900g PCGe

12. Threshold & Efficiencies & Background for 20g ULEGe (2007)
Dark Matter Searches Analysis
220 eV
ULEGe (5g×4)
@ KS
CRESST-I
@ GS
E ( keV )
Event kg-1 keV-1 day -1
HPGe-1 kg
CoGeNT(2008)
Sub-keV Background:
Not fully explained with conventional background modeling
Intense work on hardware, software and data taking at new underground site

13. Limits on Low Mass WIMPs :
Spin-Dependent & Independent Couplings (PRDRC09)
CRESST-I
CDMS(Si)
CDMS(Soudan)

14. My Contributions to TEXONO
Deputy Coordinator in Kuo-Sheng Reactor Neutrino Laboratory
- Hardware Operation/ Installation for various Detectors
- Monitoring of Detector Status
- Detector Calibration
- Contact Person at NPII for TEXONO group
Core Member of Data Analysis
- Consultation for students
- Pulse Shape Discrimination
- Designed & Built the optimized cuts for various subjects
for TEXONO & CDEX in KSNL & CJPL
- Implemented on-line PSD cuts for FPGA
Background Understanding
- 73Ge* transition (MS Thesis)
- Surface/Bulk Cuts for Point-Contact Germanium Detector
Training & Educating
- Ensure relevant skill-sets and know-hows are passed on to new members
- Supervise new members & summer students
- Conducted demonstration of Cosmic Ray Telescope to high school students

15. Status and Plans
CJPL is the deepest operating underground laboratory in the world. Physics data taking started in Feb 2011.
CDEX-TEXONO Dark Matter CJPL focuses on sub-keV Ge detectors and low-mass WIMP region.
Intense efforts on Detector R&D + Background sub-keV. Plans:
: 20-g ULEGe& 1-kg PCGe
: 10-kg range PCGe array,with Liquid Argon Anti-Compton
2015 & Beyond: Towards 1-ton scale experiment, may include Double Beta Decay to Physics program
Goals : Hope my experiences can complement existing expertise in GERDA experiment and help me make tangible contributions!!

16. Backup Slides

17. Typical Performance: The Summary

18. World Status: Summary Table
ne-e-
Energy (MeV)
Events
7 - 60
236
191
3.0 – 4.5
381 71
1.5 – 3.0
N/A
3.15 – 5.18
Experiment
LAMPF
[Liquid Scin.]
LSND
Savannah-River
[Plastic Scin.]
Re-analysed
(PRD1989, Engel&Vogel)
Krasnoyarsk
(Fluorocarbon)
Cross-Section
sin2qW
[10.0 ± 1.5 ± 0.9]
x Ene10-45cm2
0.249 ± 0.063
[10.1 ± 1.1 ± 1.0]
0.248 ± 0.051
[0.86 ± 0.25] x sV-A
[1.70 ± 0.44] x sV-A
0.29 ± 0.05
[4.5 ± 2.4]
x cm2/fission
0.22 ± 0.75
0.6 – 2.0 41
Rovno
[Si(Li)]
[1.26 ± 0.62]
x cm2/fission
0.7 – 2.0 68
MUNU
[CF4(gas)]
1.07 ± 0.34
events day-1
3 - 8
~ 450
TEXONO
[CsI(Tl) Scin.]
[1.18 ± 0.29 ± 0.08]
x RSM
0.264 ± 0.042
[1.35 ± 0.4] x sSM
[2.0 ± 0.5] x sSM

19. 500g PCGe – Threshold & Selection Efficiency
320 eV
Trigger :
ACV-Tagged eV

20. Discrimination on the Surface and Bulk events (> 2 keV)
Signal candidates (CRV+ACV)
Timing Amp (fast) pulse shapes at 200 MHz FADC
Surface Vs Bulk events down to 2 keV
n+ “inactive layer” is not totally dead; signals finite
ACV+CRT events (neutron rich) samples do not show surface band
g-rich background (CRV+ACT)
Raw pulse
n-rich background (CRT+ACV)
Smoothed
Shape 20

21. Current Status of CJPL
>9km
Ventilation Pipe

22. Behind the Scenes… This Ph.D. candidate Part of Copper Bricks…
Small Portion of Lead Bricks…

23. Good Supporting Infrastructures
Road from Xichang (西昌)
Tunnel Entrance
Campsite #2
Campsite #1

24. Neutrino-Nucleus Coherent Scattering
A fundamental neutrino interaction never been experimentally observed
σ  ~N2 applicable at Eν< 50 MeV where q2r2 << 1
a sensitive test to Standard Model
an important interaction/energy loss channel in astrophysics media
a promising new detection channel for neutrinos, relative compact detectors possible (implications to reactor monitoring) ; the channel on WIMP direct detection
Typical rate for Ge at KS ~1 kg-1day-1 where at 250 eV of threshold & Q.F. = 0.25 ; ~10 kg-1day-1 where at 100 eV of threshold & Q.F. = 0.2

25. Data Analysis : Event Selection
Reactor OFF
CUTS
(3 - 8 MeV)
Efficiencies
DAQ Live Time Eff.
~ 90%
CRV
92.7 %
MHV
99.9 %
PSD
~100 %
Z-pos
80%
Total
77.1 %

26. Background Understanding & Suppression
Main Background :
Untagged cosmic ray
 CRV efficiency
Ambience g
 3-hit pair production
Convoluted cascade 208Tl
 multi-hit analysis
External
Internal 208Tl α β
Internal
Nucl. Instr. and Meth. A