Download A Mineral Oil Monitoring System for the Daya Bay Neutrino Experiment

A Mineral Oil Monitoring System for the Daya Bay Neutrino Experiment
LIN Yanchang
LIN Yanchang
Antineutrino Detector
¾ Daya Bay goal:
sin2(2 θ13)=0.01;
¾ 8 AD modules:
4 in far hall,
2 X 2 in
i near hall;
h ll
¾ Inside AD:
3 zones, 192 PMTs;
¾ 2 calibration Sys.:
Liquid Scintillator,
Mineral Oil.
On behalf of the Daya Bay Collaboration
Bay Collaboration
On behalf of the Daya
MO clarity
box on AD lid
The University
of Hong Kong
The Chinese University
of Hong Kong
Configuration
AD lid
retroreflector
Retroreflector
PMT signal
Retroreflector in AD
¾ Light source:
LED + monochromator;
Multiple wavelength: 400~440 nm;
Narrow bandwidth: ±5 nm;
¾ Readout: 2” PMT + FADC.
AD module
MO clarity box
I1: reflected signal intensity;
I0: reference signal intensity;
A: acc
acceptance
ptanc angle
ang ratio;
rat o;
L: path length in MO;
α: the attenuation length.
αMO(m)
No. of Photons received within 35~60 ns after pulsing the LED(300k pulses of 7200 photons)
∆I
I_1=7117268
‐‐
I_2=3483830
I_3=3821063
I_4=4376387
‐15.38 %
‐7.19 %
6.29 %
¾ Simulation using GEANT4;
¾ Statistical error:~0.05%;
¾ Mean path length in MO by simulation = 8.4 m
→ ∆I/I~0.7
~0 7 ∆αMO/αMO agrees with simulation results;
¾ Requirement of monitoring αMO to <15%
→ need to monitor ∆I/I to better than 10%.
Prototype
40 ns
R Ratio (reflection/reference
e)
12.2625 (baseline)
9.81 (0.8 ×)
11.03 (0.9×)
13.48 (1.1×)
Retroreflector
Reflected Signal
R Ratio (reflection
n/reference)
MO attenuation change simulation
Reference
Signal
¾ Based on 4 m PVC pipe;
¾ MO filled;
¾ Clarity box and retroreflector installed.
¾ Long-term stability better than 1.8% in
31h test;
¾ Precision:
Design requirement: < 10%;
Total precision from prototype: < 4%.
The 24th International Conference in Neutrino Physics and Astrophysics, Athens, Greece