Neutrino Physics and Dark Matter Physics with Ultra-Low-Energy Germanium Detector Overview of TEXONO Collaboration Kuo-Sheng Reactor Neutrino Laboratory Results on Neutrino Magnetic Moments & status on Neut rino-Electron Elastic Scattering Physics & Requirements for ULE-HPGe R&D projects on ULE-HPGe Prototypes Plans Lin, Shin-Ted/ 林林林 On Behalf of Taiwan Experiment On NeutrinO (TEXONO) Colla boration Institute of Physics, Academia Sinica / @ 5th Italian-Sin
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Neutrino Physics and Dark Matter Physics with Ultra-Low-Energy Germanium Detector Overview of TEXONO Collaboration Kuo-Sheng Reactor Neutrino Laboratory.
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Neutrino Physics and Dark Matter Physics with
Ultra-Low-Energy Germanium Detector
Overview of TEXONO Collaboration
Kuo-Sheng Reactor Neutrino Laboratory
Results on Neutrino Magnetic Moments & status on Neutrino-Electron Elastic Scattering
Physics & Requirements for ULE-HPGe
R&D projects on ULE-HPGe Prototypes
Plans
Lin, Shin-Ted/ 林欣德
On Behalf of Taiwan Experiment On NeutrinO (TEXONO) Collaboration Institute of Physics, Academia Sinica / @ 5th Italian-Sino Workshop on Relativistic Astrophysics
The limit based on 570.7/127.8 days of Reactor ON/OFF: e) <7.4 X 10-11 B (90% CL) @ PRD 75 2007
Results on neutrino magnetic moment
Search of at low threshold high signal rate & robustness:
Gemma prelim. Result:e) <5.4 X 10-11 B (90% CL) @hep-ex0705.4576v1
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11)(2
ETmedT
de
Neutrino radiative decay
13
ee scattering
However, SM >>MM at few MeV ! The differential cross section can be represented
SM MM
CsI(Tl) Array (~200 kg) : e)
Z =40 cm
Single Crystal QL Vs QR
(Raw Data)
Region of Interest for SM e)
Z = 0 cm
208Tl
40K 137Cs
Data analysis under way ..
(~40000/~12000 day-kg for ON/OFF in PII to PV)
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Status of neutrino-electron scattering
Background understanding
and suppression
--Multiple-hit analysis (Cosmic ray tagged, cascades of 208Th )
=>sin2w
more data
Global analysis of all spectra
Expect:
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“Ultra-Low-Energy” HPGe Detectors ULEGe – developed for soft X-rays detection ; easy & inexpensiv
e & robust operation Prototypes built and studied :
5 g @ Y2L 4 X 5 g @ KS/Y2L 10 g @ AS/CIAE Segmented 180 g @ KS PC-500 g single element @AS
Physics for O[100 eV threhold1 kg mass1 cpd detector] :
N coherent scattering Low-mass WIMP searches Improve sensitivities on [ search ~10-11 B ] Implications on reactor operation monitoring Open new detector window & detection channel available
for surprises
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ULEGe-Prototype built & being studied :
5 g 10 g 4 X 5 g
Signal side
High Voltage side
A B
AB view
A B
43mm
43m
m10 m
m
20mm
20m
m
S3
S1
S2
S4
Segmented 180 g with dual readout
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A fundamental neutrino interaction never been experimentally-observed
~N2 applicable at E<50 MeV ( Take Q.F. =0.25, S/N >1 at 250 eV of threshold;
At threshold 100 eV-> 11 count /day/ kg)
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)
involves new energy range at low energy, many experimental challenges & much room to look for scientific surprises
Neutrino-Nucleus Coherent Scattering
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Characteristics of WIMP signal
• Scattering off nuclei• A2 dependence
– coherence loss– relative rates
• MW relative to MN
– large MW - lose mass sensitivity– if ~100 GeV
• Present limits on rate
– WIMP mass if not too heavy• different targets• accelerator measurements
– galactic origin• annual modulation• directional
cour
tesy
of G
aits
kell
recoil energy, ER (keV)
dR/d
E R
from
Jun
gman
et a
l.Vary MW for MN=73
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Sensitivity Plot for CDM-WIMP direct search
Low (<10 GeV) WIMP Mass / Sub-keV Recoil Energy : Not favored by the most-explored specific models on galactic-bound SUSY-neu
tralinos as CDM ; still allowed by generic SUSY Solar-system bound WIMPs require lower recoil energy detection Other candidates favoring low recoils exist: e.g. non-pointlike SUSY Q-balls. Less explored experimentally