Low Energy Neutrino Physics at the Kuo-Sheng Nuclear Power Plant

Overview of TEXONO Collaboration

Kuo-Sheng Reactor Neutrino Laboratory

Results on Neutrino Magnetic Moments

R&D projects towards Neutrino-Nucleus Coherent Scattering

Survey of Other Research Program (KS and non-KS based)

Summary & OutlookHenry T. Wong / 王子敬

Academia Sinica / 中央研究院

@

TEXONO Collaboration

Collaboration : Taiwan (AS, INER, KSNPS, NTU) ; China (IHEP, CIAE, THU, NJU) ; Turkey (METU) ; USA (UMD)

Program: Low Energy Neutrino & Astroparticle Physics

Kuo-Sheng (KS) Reactor Neutrino Laboratory reactor : high flux of low energy electron anti-neutrinos oscillation expts. m0 anomalous properties & intera

ctions physics full of surprises , need intense -source

※ study/constraint new regime wherever experimentally accessible

※ explore possible new detection channels Diversified R&D Projects

Taiwan EXperiment On NeutrinO

Poineering Efforts : “Zero-Background Experiment” ! KS Expt: 1st large-scale particle physics experiment in Taiwan

TEXONO Coll. : 1st big research Coll. % Taiwan & China

Kuo-Sheng Nuclear Power Plant

KS NPS-II : 2 cores 2.9 GW

KS Lab: 28 m from core#1

Kuo Sheng Reactor Neutrino Laboratory

Front Gate

Configuration: Modest yet Unique

Flexible Design: Allows different detectors conf. for different physics

Inner Target Volume

Front View (cosmic vetos, shieldings, control room …..)

R&D : Coh. (N)

T < 1 keV Results & More Data:

(e)

T ~ 1-100 keV

On-Going Data Taking & Analysis SM (e)

T > 2 MeV

Reactor Neutrino Interaction Cross-Sections

massquality Detector requirements

KS Expt: Period I,II,III Detectors

FADC Readout

[16 ch., 20 MHz, 8 bit]

ULB-HPGe [1 kg] CsI(Tl) Array

Multi-Disks Array [600 Gb]

fundamental neutrino properties & interactions ; necessary consequences of neutrino masses/mixings ; in principle can differentiate Dirac/Majorana neutrinos (D/M)

look for surprises and/or constrain parameter space for model-building with future precision oscillation data

explore new neutrino sources ; understand known ones explore new detection channels & techniques, esp. @ low energy explore roles of neutrinos in astrophysics

Neutrino Electromagnetic Properties : Magnetic Moments

e.g.

requires m0

Magnetic Moment Searches @ KS

simple compact all-solid design : HPGe (mass 1 kg) enclosed by active NaI/CsI anti-Compton, further by passive shieldings & cosmic veto

selection: single-event after cosmic-veto, anti-Comp., PSD

TEXONO data (4712/1250 hours ON/OFF) [PRL 90, 2003] background comparable to under

ground CDM experiment : ~ 1 day-1keV-1kg-1 (cpd)

DAQ threshold 5 keV analysis threshold 12 keV

Combined Analysis with all Information :

Denote

Limit:e) < 1.0 X 10-10 B (90% CL)

X 3 data volume : expect sensitivity range

e) 8 X 10-11 B

supression ; spectracut g ; SM

; cutsafter before, 1,2 ; OFFf ; ONg

1

2

1

22

1

g

g

f

g

fg

1contour

ON-OFF only

Search of at low energy high signal rate & robustness:

>>SM [ decouple irreducible bkg unknown sources ] T << E d/dT depends on total flux but NOT spectral

shape [ flux well known : ~6 fission- ~1.2 238U capture-per fission ]

22

11)(2

ETmedT

de

Couplings : Neutrino Radiative Decays

a fundamental neutrino interaction never been experimentally-observed

~N2 applicable at E<50 MeV where q2r2<1 a sensitive test to Stardard Model an important interaction/energy loss channel in astrophysics m

edia a promising new detection channel for neutrinos, without strict

lower bound on E & the channel for WIMP direct detection ! involves new energy range at low energy, many experimental c

hallenges & much room to look for scientific surprises

Standard Model Cross-Sections:

Neutrino-Nucleus Coherent Scattering

“Ultra-Low-Energy” HPGe Prototype

ULEGe – developed for soft X-rays detection ; easy & inexpensive & robust operation

Prototype : (I) 5 g ; (II) 4 X 5 g ; (III) 10 g ; (IV) segmented 20 g

threshold <100 eV after modest PSD [lowest achieved for bulk radiation detectors]

study feasibilities for 1-kg-ish detector for coherent scattering and Dark Matter searches [ search a by-product ]

5 g

4 X 5 g

ULE-HPGe Prototype Results

※ threshold ~100 eV , calibration by linear extrapolation from 1-6 keV

※ PSD possible to suppress noise edge

Threshold ~ 100 eV

Yangyang ( 襄陽 ) Lab (Y2L)min. 700 m of rock overburden

Install 5 g ULB-ULEGe at Y2L on January 2005

Study background and feasibility for CDM searches

may evolve into a full-scale (1 kg) CDM experiment

TEXONO KIMS @ Y2L

Sensitivity Plot for CDM-WIMP search with

1 kg ULEGe at 100 eV threshold ………

Background Measurements & Comparisons

Similar background at KS & Y2L Apparent difference between 5 g & 1 kg due to scaling with s

urface area instead, reproduced in simulations i.e. background can be ~ O(1 cpd) at > 1 keV range for 1 kg ULE

Ge in compact array form New detection channel in Unexplored kinematic regime :

“don’t know what to expect and what are expected”

(keV)

First-Ever Low Background Data down to 100 eV ……. !

….. More data taking & analysis underway

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……..

Electron Neutrinos @ Reactor (PRD 72, 2005)

Nuclear material

Fission products

n rich nuclei

n rich nuclei

Stable isotopeStable isotope

Structure materialn

decay

decay

EC EC

even-even

Electron neutrino emission

electron anti-neutrino

emission

Evaluate e flux at standard reactors

Derive limits on and for e

Explore e flux enhancement in loaded reactor (e.g. with Cr)

Study Potential applications : eNCC cross-section meas

urements, 13 Pu-production monitoring

Tagging of 73Ge ½- 2 transitions

Event-by-Event background-free tag with PSD

To do : Reactor ON/OFF analysis on the system ~1 s before/after the transition

-induced events signature: excess in the “ON+before” spectra

Looking for -induced 73Ge*

Reactor Axions Analysis with HPGe data

Reactor core has intense M1 transitions : e.g. 7

Li, 91Y, 97Nb etc. Signature : peak at tra

nsition energy at HPGe due to Primakoff conversion

Like TEXONO HPGe

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 used in TPC in LEPS Expt. @ SPring8

TPC for LEPS @ SPring8

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.

Mixed signal FADC Adapter Board

TEXONO/KS FADC for SPring8/LEPS

(cosmic muon)

Trace Radio-purity with AMS

Based at AMS facilities @CIAE with 13 MV Tandem

Potential Merits:

small samples, quick

versatile on sample choice

sensitive to emitters

sensitive to stable isotope & extrapolate (e.g. 39K)

>103 improvements over ICP-MS

[.. once prescriptions are known. ]

Status : demonstrate 129I/127I < 10-12 g/g

measure 40K~10-10 g/g in CsI (powder)

develop techniques for K in liquid scintillator

Sensitivity goal : < 10-16 g/g

Future : 87Rb …… [238U / 232Th series after Tandem upgrade]

Sonoluminescence Project

SonoLum Pulse

a frontier subject with possible surprises

new directions : to explore subjects we do not know

inter-disciplinary research

new research style and experience enriching

Table-top experiments, pursue-able in several labs

balance the other big & long time-scale projects

use HEP approaches

Focus :

understand physics mechanism

emissions of high energy radiations

TEXONO Collaboration: Built-Up from Scratch & Maturing Kuo-Sheng Neutrino Lab.: Established & Operational Modular & Flexible Design Physics Data Taking since June 01 ※ Unique HPGe Low Energy Data ※ Bkg Level ~ Underground CDM ExptResults published on & reactor e

Summary & Outlook

Diversified Program in Parallel Main Thrust on ~200 kg CsI(Tl) [(e) …] ULEGe: for coh(N) + CDM Present Focus of Collaborating Groups: AS :: -e S. Coherent S. SonoLu

m.CIAE :: AMS SonoLum.

THU :: CDM SearchReaching Out Y2L @ Korea / Daya Bay Project (?) / Regional Framework

TEXONO is a (modest) part of world neutrino physics community

Tremendous Pleasure & Pressure !