Measurement of Neutrino- Electron Scattering with CsI(Tl) Scintillators at the Kuo-Sheng Neutrino Laboratory Academia Sinica Seminar Taipei, TAIWAN, 21 May 2010 Muhammed Deniz 1,2 1: IoP, Academia Sinica, Taiwan 2: METU, Ankara, Turkey On behalf of TEXONO Collaboration
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Measurement of Neutrino-Electron Scattering with CsI(Tl) Scintillators at the Kuo-Sheng Neutrino Laboratory Academia Sinica Seminar Taipei, TAIWAN, 21.
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Measurement of Neutrino-Electron Scattering with CsI(Tl) Scintillators at the
Kuo-Sheng Neutrino Laboratory
Academia Sinica Seminar
Taipei, TAIWAN, 21 May 2010
Muhammed Deniz1,2
1: IoP, Academia Sinica, Taiwan 2: METU, Ankara, Turkey
On behalf of TEXONO Collaboration
• Theory overview Theory overview e e – e– e- - Scattering – MotivationScattering – Motivation
• Cross Section Cross Section && EW Parameters – World Status EW Parameters – World Status
Program:Program: Low Energy Neutrino & Astroparticle PhysicsLow Energy Neutrino & Astroparticle Physics
[1] Magnetic Moment Search at ~10 keV PRL 2003, PRD 2007 [2] Cross-Section and EW Parameters measurement at MeV range PRD 2010[3] e N Coherent Scattering & WIMP Search at sub keV range
Taiwan EXperiment On
NeutrinO
massquality
Detector requirements[3]
[2]
[1]
Measurement of Neutrino-Electron Scattering 7/43
TEXONO Physics Program on CsI(Tl) detector
• attempt a measurement of Standard Model ee
sin2w at MeV range
Measurement : Recoil Energy of e
• attempt a measurement of Standard Model ee
sin2w at MeV range
Measurement : Recoil Energy of e
e + e- e + e-
Reactor : high flux of low energy (MeV range) electron anti-neutrinos.
properties are not fully understood intense -source
• Region of Interest for e - e scattering
Big uncertainties of modeling in the low energy part of reactor neutrino for SM (ee) higher energies (T>3 MeV)
• Region of Interest for e - e scattering
Big uncertainties of modeling in the low energy part of reactor neutrino for SM (ee) higher energies (T>3 MeV)
(less ambient background & reactor e spectra well known)
Data Volume: ~ 29883 kg-day / 7369 kg-day ON/OFF
Measurement of Neutrino-Electron Scattering 11/43
KS CsI(Tl) Experiment Configuration
Multi-Disks Array (several Tb)
CsI(Tl) (200 kg) Connecting Board
FADC Readout
16 ch., 20 MHz, 8 bit
Measurement of Neutrino-Electron Scattering 12/43
Dynamic Range of FADC
Unsaturated
Saturated
Goal: to reconstruct the missing part of the saturated pulse to get the charge and energy.
Single Crystal QL vs QR (Raw Data)
Region of Interest for SM ee)
Z = 0 cm
208Tl
40K 137Cs QL
QR
Z =40 cm
Nucl. Instr. and Meth. A 511 (2003) 408-416.
Measurement of Neutrino-Electron Scattering 13/43
Data Analysis: Event Selection
CUTS
(3 - 8 MeV)
Efficiencies
DAQ Live Time Eff.
~ 90%
CRV
92.7 %
MHV
99.9 %
PSD
~100 %
Z-pos
80%
Total
77.1 %
MeV 3at 30
1
B
S
Measurement of Neutrino-Electron Scattering 14/43
Decays of radioactive contaminants mainly 232Th and 238U decay chain produce background in the region of interest. Estimate the abundance of 137Cs, 238U and 232Th inside the detector.
IDEA: By monitoring the timing and position information related β-α or α-α events can provide distinct signature to identify the decay process and the consistency of the isotopes involved.
A. Radioactive Contaminants
Background Understanding
Cosmic Ray muons, Products of cosmic ray muons, Spallation neutrons and High Energy ‘s from such as 63Cu, 208Tl
IDEA: multiple-hit analysis can give us very good understanding 208Tl, High Energy and cosmic related background in the region of interest.
Cosmic & High Energy Gamma
- By comparing cosmic and non-cosmic multiple-hit spectra.
Tl-208
- By examining multiple-hit spectra as well as simulation of Tl-208 decay chain energies to understand/suppress background in the region of 3-4 MeV.
B. Environmental Backgrounds
Measurement of Neutrino-Electron Scattering 15/43
Intrinsic 137Cs Level
137Cs contamination level in CsI was drived ==> (1.55 ± 0.02 ) X 10-17 g/g
31.3 kg-day of CsI(Tl) data was analysed.
Nucl. Instr. and Meth. A 557 (2006) 490-500.
Measurement of Neutrino-Electron Scattering 16/43
β
α
Data: The total of 40 crystals with data size of 1725 kg·day was analyzed.
i) 214Bi(-)→ 214Po(,164s) → 210Pb
Intrinsic U and Th Contamination Level
T1/2 = (163 ±8) s
238U abundance = 0.82 ± 0.02 x10-12 g/g
iii) 220Rn → 216Po0.15s) → 212Pb
T1/2 = (±s
232Th abundance2.23 ± 0.06 x 10-12 g/g
ii) 212Bi(-,64%) → 212Po(, 299ns) → 208PbSelection: - pulse followed by a large pulseSelection: 1st pulse is shaped &
2nd pulse shaped
Selection: two events with time delay less than 1s
─ mass models all mechanisms carry modifications to the structure of the standard EW NC& CC
NSI of Neutrino
Measurement of Neutrino-Electron Scattering 35/43
─ e e – e– e- - scattering provide a sensitive tool to probe NSIscattering provide a sensitive tool to probe NSI
Comparison of Bounds of NSI Parameters
Measurement of Neutrino-Electron Scattering 36/43
1. Exchange of Scalar Unparticles
i= 0(1) : Unparticle scalar/vector field
: Scalar(Vector) unparticle couplings
f : e, u, d
denotes neutrino flavours
d: Unparticle mass dimension
: Unparticle energy scale
Unparticles
2. Exchange of Vector Unparticles
For the flavour changing case:
For the flavour conserving case
Measurement of Neutrino-Electron Scattering 37/43
The notion of unparticles is introduced by Howard Georgi . A scale invariant sector which decouples at a suffciently large energy scale exists. (Phys. Rev. Lett. 98, 221601 (2007)
The signatures of Unparticle Physics can also be observed by reactor neutrinos by searching the effects of virtual unparticle exchange between fermionic currents.
This interaction can be either exchange of Scalar Unparticles or Vector Unparticles.
Unparticle physics is a speculative theory that conjectures matter that can not be explained in terms of particles, because its components are “scale invariant”, a property of fractals.
A fractal is a rough or fragmented geometric
shape that can be split into parts, each of which is
(at least approximately) a reduced-size copy of
the whole," a property called self-similarity.
“Scale invariance” is a feature of objects or laws that do not change if length scales (or energy scales) are multiplied by a common factor.
Unparticle Physics
Measurement of Neutrino-Electron Scattering 38/43
Unparticles
Measurement of Neutrino-Electron Scattering 39/43
+ e- UP + e-
Unparticle – Exclusion Plots
Measurement of Neutrino-Electron Scattering 40/43
Scalar Unparticle – Preliminary Results
Measurement of Neutrino-Electron Scattering 41/43
Results are improved over those from Borexino and MUNU experiments
Unparticle effects decreases as U increases
Vector Unparticle – Preliminary Results
Measurement of Neutrino-Electron Scattering 42/43
Summary
Detector: CsI(Tl) Scintillating Crystal Array (~ 200 kg)
Threshold: 3 MeV
Analysis Results:
(e – e-) with ~ 25% accuracy
Weak Mixing Angle with ~ 15% accuracy
Verify SM negative interference
sensitivity ~ 10-10 B
neutrino charge radius sensitivity ~ 10-32 cm2
Probing new Physics : NSI and UP -- Preliminary
Current bounds are improved over those from the previous experiments