-ray detector CATANA for E1 response of neutron-rich nuclei Tokyo - - PowerPoint PPT Presentation

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ray detector catana for e1 response of neutron rich nuclei
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-ray detector CATANA for E1 response of neutron-rich nuclei Tokyo - - PowerPoint PPT Presentation

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-ray detector CATANA for E1 response of neutron-rich nuclei Tokyo Institute of Technology Yasuhiro Togano 10 March, ELPH calorimeter workshop E1 response of n-rich nuclei nuclei B(E1) strength Pygmy: Ex~10 MeV Giant: Ex~80A -1/3 MeV ~5% of TRK

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SLIDE 1

γ -ray detector CATANA for E1 response of neutron-rich nuclei

Tokyo Institute of Technology Yasuhiro Togano

10 March, ELPH calorimeter workshop

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SLIDE 2

E1 response of n-rich nuclei

  • Giant dipole resonance (GDR): all stable nuclei
  • Pygmy dipole resonance (PDR): n-rich nuclei (208Pb, 132Sn

etc…)

  • Oscillation of neutron skin?
  • EOS of neutron matter → neutron star
  • Structure is not yet known

Excitation energy [MeV] B(E1) strength

Pygmy: Ex~10 MeV ~5% of TRK sum

Sn

Light(γ)

nuclei

Giant: Ex~80A-1/3 MeV ~100% of TRK sum

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SLIDE 3

Measurements of PDR

  • D. Savran et al., Prog. Part. Nucl. Phys. 70, 210 (2013).

N=82 Z=50 Z=40 Z=28 Z=20

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SLIDE 4

Measurements of PDR

  • D. Savran et al., Prog. Part. Nucl. Phys. 70, 210 (2013).

N=82 Z=50 Z=40 Z=28 Z=20

Difgerence of Fermi surface

Measurement of PDR in 48,50,52Ca@RIBF

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SLIDE 5

Experimental procedure

Eγ

β~0.6 virtual photon absorption

n

51Ca 52Ca 52Ca

Eγ2

Pb

Eγ1

52Ca 51Ca+n

Erel Eγ1 Eγ2 Sn

52Ca 52Ca

Pb

52Ca 52Ca

Eγ

~2% γ branch

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SLIDE 6

Experimental setup

52Ca

250 MeV/nucleon n

51Ca

CATANA CsI(Na) array

in 2016

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SLIDE 7

CATANA

  • CAesium iodide array for γ-ray Transitions in

Atomic Nuclei at high isospin Asymmetry

  • Crystal: CsI(Na), 20 crystals per ring
  • High effjciency: ~60% for 1 MeV gamma

Beam

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SLIDE 8

Structure of CATANA

  • Doppler shift & Lorentz boost
  • Forward focus

40 cm 20 cm Angular resolution: ~9 deg

15 cm t 9 cm t θ

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SLIDE 9

CATANAの結晶

  • CsI(Na)
  • Better time response
  • Fit PMT’s spectral response
  • hygroscopic: housing
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SLIDE 10

Supporting frame

Beam

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SLIDE 11

Supporting frame

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SLIDE 12

PMT

  • R11265
  • Length: 3.5 cm: less space
  • Metal package ← magnetic field
  • B-field@SAMURAI target area
  • 30 G

R580 R11265

R580 R11265

R580 R11265

Cathode efgective area

34 mm Φ 23

Photocathode material

Bialkali Super Bialkali

Number of dynodes

10 12

Gain

1.1 1

Dark current

3 nA 0.4 nA

Rise / Transit time

2.7 / 37 ns 0.6 / 5.1 ns

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SLIDE 13

Test of prototypes

511 keV 1275 keV

Position: light collection effjciency

polished etched Calorimetric property

  • Etched surface
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SLIDE 14

Test of prototypes

Response to 8.99 MeV γ ray

252Cf

polyethylene 10 x 20 mm2 Ni plate

58Ni + n 59Ni

8.99 MeV

blue: w Ni plate red: w/o Ni plate

channel

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SLIDE 15

Schedule

  • ~Mar. 2015: Design of supporting frames
  • ~Dec. 2015: 100 crystals
  • Apr. 2016?:Measurement of E1 response in

48,50,52Ca by combining NaI(Tl) and LaBr3

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SLIDE 16

Summary

  • New γ-ray detector array CATANA
  • CATANA + SAMURAI → E1 response of n-rich

nuclei.

  • Prototype test: finished
  • Ca experiment: April 2016?