Basics (Collaboration; Laboratory; Physics)

Experiment (Detector; Analysis; Electroweak Physics)

Probing Non-Standard Interactions

Sensitivity Projections

Measurement of Neutrino-Electron Scattering and Electroweak Parameters at

Kuo-Sheng Reactor Laboratory

Henry T. Wong /王子敬

Academia Sinica /中央研究院

September 2011

@

TEXONO Neutrino Physics @ KSNLTEXONO Collaboration: Taiwan (AS,INER,KSNPS,NTHU);

China (THU,IHEP,CIAE,NKU,SCU); Turkey (METU, KTU); India (BHU)Program: Low Energy Neutrino & Dark Matter Physics

massquality Detector requirements

[3]

[2]

[1]

Magnetic Moments (PRL03,PRD07)

νNCo

here

nt S

catt

erin

g

Dar

k M

atte

r Se

arch

es

(PRD

-RC0

9) Standard Model νe Scattering (2 ⊗ PRD10)

Observable Spectra with Reactor Neutrino “Beam”

This Talk

•3

28 m from core#1 @ 2.9 GW

Shallow site : ~30 mwe overburden

Kuo Sheng Reactor Neutrino Laboratory

νe – e- Scattering

νe + e- νe + e- A basic SM process with CC, NC & Interference

Not well-studied in reactor energy range ~ MeV

stronger NC component than νe ⇒ better sensitivities to sin2θw

SM Formulation

CsI(Tl) Scintillating Crystal Array

CsI(Tl) : 9x12 ArrayReal/Fid. Mass : 187/57 kg kg

Merits: proton free target

(suppress νe-p background)

scalable to ϑ (10 tons)

good energy resolution, α/γ Pulse Shape Discrimination (PSD)

allows measure energy, position, multiplicity

better information for background understanding & suppression

Energy : Total Light Collection

σ (E) ~ 6% @ E>660 keV

Z-position : Left/Right PMT Ratio

σ (Z) ~ 1.3 cm @ E>660 keV

RL QQE ×≈

( ) ( )RLRL QQQQZ +−≈ /

Data Volume: ~ 29883 kg-day / 7369 kg-day Reactor ON/OFF

DAQ Threshold: 500 keV / Analysis Threshold: 3 MeV

[ less ambient background & reactor spectra well known ]

RAW DATA – PMT Left & Right

Event Selection

MeV 3at 301

≅BS

Via Cosmic-Ray Veto (CRV) ; Multi-Hit Veto (MHV) ; γ/αpulse shape (PSD) , and surface/ bulk (Z-Pos)

Background Understanding & Suppression

Main Background:untagged cosmic-ray CRV eff.ambient γ 3-hit pair-productionconvoluted cascade 208Tl multi-hit

OFF-BKG

ON-BKG

SMRsysstatR ×±±= )](16.0)( 21.008.1[

Electroweak Physics Measurements

SMRsysstatR ×±±= )](16.0)( 21.008.1[

)(024.0)(031.0251.0sin2 sysstatW ±±=θ

Verify SM Destructive Interference

INCCCSM RRRR ×++= η

@ 90% C. L.

232232 103.3101.2 cmre

−− ×<<×− ν

Bµµν ××< −10102.2Neutrino Magnetic Moment

Neutrino Charge Radius

[ cf HPGe @ 12 keV threshold ] Bµµν ××< −101074.0

Results : Summary Table

νe−e-

νe−e-

Energy (MeV) Events

7 - 60 236

10 - 50 191

1.5 - 3.03.0 – 4.5

38171

1.5 – 3.03.0 – 4.5 N/A

3.15 – 5.18 N/A

Experiment

LAMPF[Liquid Scin.]

LSND[Liquid Scin.]

Savannah-River[Plastic Scin.]

Savannah-River Re-analysed

(PRD1989, Engel&Vogel)

Krasnoyarsk(Fluorocarbon)

Cross-Section sin2θW

[10.0 ± 1.5 ± 0.9]x Eνe10-45cm2 0.249 ± 0.063

[10.1 ± 1.1 ± 1.0]x Eνe10-45cm2 0.248 ± 0.051

[0.86 ± 0.25] x σV-A[1.70 ± 0.44] x σV-A

0.29 ± 0.05

N/A

[4.5 ± 2.4]x 10-46 cm2/fission 0.22 ± 0.75

0.6 – 2.0 41Rovno[Si(Li)]

[1.26 ± 0.62]x 10-44 cm2/fission N/A

0.7 – 2.0 68MUNU[CF4(gas)]

1.07 ± 0.34 events day-1 N/A

3 - 8 ~ 410TEXONO[CsI(Tl) Scin.]

[1.08 ± 0.21 ± 0.16] x RSM

0.251 ± 0.039

[1.35 ± 0.4] x σSM[2.0 ± 0.5] x σSM

ν-e : purely leptonic process & robust SM predictions Ideal to Probe New Physics

Model independent formulation as four-fermion NSI couplings

Probing Non Standard Interactions (NSI)

Non-Universal :

Flavor-Changing :

Bounds on NSI Parameters

Other New Physics : Unparticle Physics ; Non-Commutative Geometry ……

Sensitivities Projections

CsI(Tl) scalable to ~O(10 tons)

Intrinsic radioactivity < 1/10 ν-e signals & measured to ~1% accuracy

External Background Dominates & Modeled to ~1% ⇒ Further Suppressed by Larger Detectors

Take: 1 ton fiducial target & 1000 days & 1/10 reduction of external background ⇒ σ(ν-e) to <1% & sin2θw to ±(0.001-0.002)

Limited by knowledge of reactor spectra @ >3 MeV⇒ [independent normalization by –p measurement]

ν e

ν e

Prospects and Plans [TEXONO- CDEX Collaboration]

Completed ν-e cross-section measurement and magnetic moments studies at shallow depth reactor laboratory KSNL.

Also placed limits WIMP- mass < 1 0 GeV with sub-keV Geprototype

R&D on Ge & background understanding at sub- keV range Dedicated dark matter searches at new deep underground

laboratory CJPL in China 2010+, first with 1kg Point-Contact Ge

Focuses at KSNL: sub-keV Ge to support dark matter program AND towards ν-N coherent scattering