Performance Evaluation of Mirror for Imaging Detector
Research Center for Neutrino Science, Tohoku University, Keigo Soma
Motivation

Large Detector

Anti-neutrino is generated inthe Earthʼs interior
β-decay

Number of Events [1/MeV]"Improve measurement accuracy ofgeo-neutrino to understand internal
structure of the Earth”

80
Analysis Window

60

Reactor-neutrino is

U-Series Geo
Th-Series Geo
Reactor

232Th→208Pb+64He+4e-+4ν +42.7[MeV]
e40K→40Ca+e-+ν +1.31[MeV]
eSearch for radiogenicdetector

heat source in the!

primary backgroundcoreEarthʼs deep interiorUThmantle

Identify the composition

40Large background2000of the mantle

Directional measurement of geo-neutrino flux from crust, mantle, and core

Earth tomography isTomography of earth’s deep interior by neutrinos

will be suppressed

238U→206Pb+84He+6e-+6ν +51.7[MeV]e++n❷ Creation points of geo-neutrino
areidentiﬁed
GeoAnti-Neutrino
Direction❶ Geo-neutrino is separated fromreactor-neutrino

enable24
68
Prompt Energy (Positron Scale) [MeV]

Small Detector
Principle inspection of directional measurement application to reactor monitorνe の入射方向に散乱θn<35° (Eνe<3MeV)
Li LiquidScintillator(LiLS)←Dissolved 6Li in LS

Imaging Detector

Li含有液体シンチレータ

γ e-＜Feature of LiLS＞

γ+e

Typical length: 40mmP

νed報

θn(Li loaded 2.0wt%)
20μs interval
Edelayed = 1.9MeV

3H

6Li

改良点

LiLS

1. 中性子位置情報を失う前に6Liが捕獲
2. α線は長距離移動出来ない

Developing Imaging Detector

LSThis poster
is about thisSecondary mirror

Design of Optics→ evaluated these optics and checked individual differences

Setup

ProducePrimary Mirror

ND filter

RailZCCD

Primary mirror

Focus plane1000mm

Dark Room0❶ Take images (focused light) with CCD camera❷ Evaluate the spread (RMS) of these images❸ Check these images and compere data with the simulation

ResultMirror1

Read out

Optics ＋ Photon detector“We produced two optics“

Secondary Mirror

Imaging detector

Property

検出原理

LED→

Scintillation light

We want to separate
2 vertex points(prompt and delayed points)

delayedsignalImprove vertex resolution
for separating 2 points

Detection principle

🔵 α-ray & 3H are delayed signalsnα🔵 6Li has large cross section

Method: combine optics
and photon detector

Mirror2

Material

RadiusThickness

Focal

Primary Secondary Primary Secondary Length

Aluminum 145mm

75mm

50mm

30mm

Plating Reﬂectance

1000mm Chrome55~65[%]

Analysis

Simulation

Example: Z=+1508

Pointdata

7

Typical value to be able to separate
two vertex points（Requirement）

450

Z=-150mm

Data※About surface : It was polished by humanʼs handRMS[mm]promptsignal400

500

6̶̶ Optics1
̶̶ Optics24005̶̶ Simulation

350
300
250

300

4200
200

150
100100350

Z=-100mm

00100

200

300

400500600

Selection of image

Z=+100mm

Z=+150mmPx i zi
ix= Pi zi
Py i ziiy= Pi zi0210−150

RM S =−100s−50⌃[(xi0x̄)2 + (yi⌃zi50100150Z[mm]ȳ)2 ] ⇥ zi

Summary & To do🔵 Two optics reproduce the design and have enough🔵 Imageʼs shape is nearly consistent🔵 Itʼs spread is slightly larger than the simulation results🔵 Image is distorted

International Workshop : Neutrino Research and Thermal
Evolution of the Earth 2016/Oct/25~27 @ Tohoku University

performance (under requirement)🔵 There are not individual differences🔵 We will think about a better method to analyze🔵 We will try to use the optics for other experiment