Performance evaluation of the detector part for development of a - PowerPoint PPT Presentation

Performance evaluation of the detector part for development of a Compton Camera 2019/12/23 Yamanaka Taku lab. Sugiura Seiya Iwata Kazushi 1

Principle first scintillator • Compton scattering 𝐹 𝛿 / 𝑛 𝑓 (1 − 𝑑𝑝𝑡𝜄 ) 𝐹 γ 𝑈 = 𝐹 𝛿 − 𝐹 ′ 𝐹 γ′ = 𝛿 = 𝐹 𝛿 1 + 𝐹 γ / 𝑛 𝑓 (1 − 𝑑𝑝𝑡𝜄 ) 1 + 𝐹 𝛿 / 𝑛 𝑓 (1 − 𝑑𝑝𝑡𝜄 ) 𝐹𝛿 , 𝐹𝛿 ′ 𝑈 ( : energys of entering or scattered γ-ray : energy of electron 𝑛 𝑓 :mass of electron 𝜄 : scattered angle of γ-ray 511keV) 𝐹 𝛿 ´ and 𝑈 ⇒ ⇒ 𝜄 2

Performance evaluation 𝑈 𝐹 γ′ [MeV] [MeV] 1.2 1.0 0.8 1.275MeV 0.8 0.6 0.4 0.662MeV 0.4 0.2 0.356MeV 0 80 120 80 120 40 θ[degree] 40 θ[degree] 3

Principle second scintillator • Photoelectric effect B.E. :binding energy 𝑓 − and 𝐹 𝐶 . 𝐹 . ⇒ ⇒ 𝐹 𝛿 ′ 4

Principle 5

Performance evaluation Using CsI scintillator(10mm×10mm×10mm) Evaluation • Angular resolution • Systematic error • Needed event rate 6

Angler resolution From Compton equation 2 2 𝜀𝐹 ′ 𝜀 (1 − 𝑑𝑝𝑡𝜄 ) 1 2 2 ( 𝜀𝑈 ( 2 𝐹 ′ 𝛿 + 𝑈 ) 𝛿 = ( ) + 𝐹 ′ 𝑈 ) 𝛿 1 − 𝑑𝑝𝑡𝜄 𝐹 ′ 𝛿 + 𝑈 𝐹 ′ 𝛿 also 𝜀𝜄 = 1 − 𝑑𝑝𝑡𝜄 × 𝜀 (1 − 𝑑𝑝𝑡𝜄 ) 1 − 𝑑𝑝𝑡𝜄 𝑡𝑗𝑜𝜄 7

０ ０ １２ ４ ０ ４ ０ ８ ０ １２ ０ ８ Angler resolution δθ[degree] δθ[degree] 10 ％ 25 ％ 40 40 30 30 20 20 10 10 θ[degree] θ[degree] 8

Estimate event rates Factors of event rates are • Compton Scattering and Photoelectric rates • Length between radioactive source and first detector, and first detector and second detector 9

Estimate event rates The intensity of photon 𝐽 = 𝐽 0 𝑓 − 𝜈𝑦 :absorption coefficient [1/cm] 𝜈 𝜈 = 𝑂𝜏 = 𝑂 ( 𝑎𝜏 comp + Φ photo + 𝜐 pair ) 𝑂 :number density of atom or molucule [1/cm 3 ] :Compton scattering [1/cm 2 ] 𝜏 comp :photoelectric effect [1/cm 2 ] Φ photo :pair production [1/cm 2 ] 𝜐 pair :pair production 𝜐 pair 𝜐 pair = 0 1.022MeV ➡ 𝐹𝛿 < 10

Estimate event rates Klein-Nishina formula 2 (1 + 𝑑𝑝𝑡 2 𝜄 + 𝑏 2 (1 − 𝑑𝑝𝑡𝜄 ) 2 𝑒 Ω = 𝑠 𝑓 2 𝑒𝜏 1 1 + 𝑏 (1 − 𝑑𝑝𝑡𝜄 ) ) 2 [ 1 + 𝑏 (1 − 𝑑𝑝𝑡𝜄 ) ] [mb] 𝜏 comp 𝐹 𝛿 𝑠 𝑓 = 2.81 × 10 − 15 𝑏 = 0.002 [m] classical electron radius, 𝑛 𝑓 0.0016 0.0012 0.0008 0.0004 40 80 120 θ[degree] 11

・ ・ ・ Estimate event rates In ScI scintillator rate 0.5 0.4 0.3 10mm 0.2 8mm 0.1 2mm 0.2 0.4 0.6 0.8 1.2 1.0 [MeV] 𝐹 γ 12

Hardware part 13

Detector • CsI crystal CsI (Tl）(Reading Edge Algorithms) size:10mm×10mm×10mm • MPPC S13360-1325CS (HAMAMATSU) photosensitive area :1.3mm×1.3mm pixel pitch : 25um →We need a detector with MPPC and CsI 14

CsI and MPPC CsI crystal Silicone cookie MPPC • Need to attach CsI and MPPC 15

BOX CsI &MPPC LEMO •Stack like this top view • Box is filled silica gel because CsI is weak to humidity • Use LEMO connector for easily detachable feature 16

CsI and MPPC and BOX CsI and MPPC assembly behind inside the box appearance behind 17

EASIROC MODULE • NIM EASIROC MODULE →64 MPPCs can be operated simultaneously Made a Flat cable to LEMO adapter board This module uses Flat cable 18

Set up 19

Future prospect gamma source 1. 2. • Measure the angular distribution • Measure the location of gamma source 20

We shall specify the location of source!! conclusion • Error and the rate were calculated • we have the necessary equipment 21

Back Up 22

Performance evaluation Prepared sources for test source γ energy Emission prob. Radioactivity Per decay 1.275 MeV 100 % 496.02 kBq Na Cs 0.662 MeV 85% 91.09 kBq Ba 0.356 MeV 62% 716.69 kBq 23

Angler resolution From Compton equation 𝑈𝑛 𝑓 1 − 𝑑𝑝𝑡𝜄 = ( 𝑈 + 𝐹 𝛿 ′ ) 𝐹 𝛿 ′ And error propagation 2 2 𝜀𝐹 ′ 𝜀 (1 − 𝑑𝑝𝑡𝜄 ) 1 2 2 ( 𝜀𝑈 ( 2 𝐹 ′ 𝛿 + 𝑈 ) 𝛿 = ( ) + 𝐹 ′ 𝑈 ) 𝛿 1 − 𝑑𝑝𝑡𝜄 𝐹 ′ 𝛿 + 𝑈 𝐹 ′ 𝛿 Also 𝜀 (1 − 𝑑𝑝𝑡𝜄 ) = 𝑡𝑗𝑜𝜄𝜀𝜄 From the above 𝜀𝜄 = 1 − 𝑑𝑝𝑡𝜄 × 𝜀 (1 − 𝑑𝑝𝑡𝜄 ) 1 − 𝑑𝑝𝑡𝜄 𝑡𝑗𝑜𝜄 24

Estimate event rates ( 𝑆𝑏𝑒𝑗𝑝𝑏𝑑𝑢𝑗𝑤𝑗𝑢𝑧 ) × 𝑠 2 Ω Ω 4 𝜌𝑠 2 25

Estimate event rates Klein-Nishina formula 2 (1 + 𝑑𝑝𝑡 2 𝜄 + 𝑏 2 (1 − 𝑑𝑝𝑡𝜄 ) 2 𝑒 Ω = 𝑠 𝑓 2 1 𝑒𝜏 1 + 𝑏 (1 − 𝑑𝑝𝑡𝜄 ) ) 2 [ 1 + 𝑏 (1 − 𝑑𝑝𝑡𝜄 ) ] 𝑠 𝑓 = 2.81 × 10 − 15 [m] classical electron radius, 𝐹 𝛿 𝑏 = 𝑛 𝑓 and total cross section is { (1 + 2 𝑏 ) 2 } 𝑏 2 [ 𝑏 ln(1 + 2 𝑏 ) ] + 1 1 + 𝑏 2(1 + 𝑏 ) 1 + 2 𝑏 − 1 1 + 3 𝑏 𝜏 𝑑 = 2 𝜌𝑠 𝑓 2 2 𝑏 ln(1 + 2 𝑏 ) − 26

Estimate event rates Each of the scintillators is in Two boxes are made with Polylactide((C 3 H 4 O 2 ) n ) two boxes Molecular weight 72n [g/mol] thickness 0.2cm ×2 cm 3 density 1.25g/ ➡ Number density of electron Transmittance 𝑜 = 𝑂𝑎 = 1.25 72 × (6.02 × 10 23 ) × 38 𝑓 − 0.4 𝑜𝜏 𝑑 = 3.97 × 10 23 [1/cm 3 ] 27

Estimate event rates Solid Angle δΩ 𝜄 + 𝜀𝜄 /2 ∫ 𝜀𝛻 = 𝑒𝛻 2 𝜌𝑡𝑗𝑜𝜄 𝜀𝜄 𝜄 − 𝜀𝜄 /2 𝜄 = 4 𝜌𝑡𝑗𝑜𝜄𝑡𝑗𝑜𝜀𝜄 𝜏 comp = 𝑒𝜏 𝑒 Ω 𝜀𝛻 28

Box size 58mm 58mm 58mm 29

CsI and MPPC size 18mm 18mm 18mm 18mm 17mm 3mm 30

Detector Desired detector conditions →I made it using 3D printer. • Detector needs drying system because CsI has deliquescence. • Cable length can be adjusted freely. • Requires CsI and MPPC fixation and alignment 31

EASIROC • NIM EASIROC MODULE → MPPC readout ASIC • The main function -64 MPPCs can be operated simultaneously -The voltage of each channel can be adjusted (0~4.5V) -Module control and DAQ can be performed by a PC via Ethernet 32

Software • Controller for EASIROC module By rewriting the numerical values in RegisterValue.yml or InputDAC.yml , we can adjust the applied voltage and select the output information Use this to control EASIROC interactively RegisterValue.yml ←(-1) mean don’t use ←(32) mean CH32 33

CsI 減衰時間 密度 融点 硬度 屈折率 ピーク波長 潮解性 僅かにあり 発光量 4.53 [g/cm^3] 621[ ℃ ] 2 [Mohs] 1.78 56000 [Photons/MeV] 1050[ns] 550 [nm] 34

Reference • (NIM EASIROC) • (MPPC) • (software of EASIROC) 35