based -ray detection array for use at RIBF - · PDF fileA Novel LaBr 3 based -ray detection...
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A Novel LaBr 3 based γ-ray detection array for use at RIBF P. Doornenbal 1 , H. Scheit 1 , N. Aoi 1 , T. Motobayashi 1 , H. Sakurai 1 , and S. Takeuchi 1 1 RIKEN Nishina Center for Accelerator-Based Science, 2-1 Hirosawa, Wako, Saitama 0351 - 0106, Japan Motivation Simulated exemplary experiments With the Radioactive Ion Beam Factory (RIBF) at RIKEN being on the cusp to deliver the worldʼs most intense RI beams at energies of several hundred MeV/u, a new γ-ray detection array is required to exploit the new experimental possibilities coming along with it. The material LaBr3(Ce) possesses an unprecedentedly high intrinsic energy resolution for scintillators of 2 % (FWHM) at 1332.5 keV and an excellent time resolution below 500 ps and is therefore well suited for high-resolution in-beam γ-ray experiments at relativistic energies. To minimize Doppler effects, the total array will comprise of up to one thousand individual crystals. The array will be placed around the secondary target area of the large acceptance fragment separator BigRIPS. Alternatively, the array can be used in a different configuration for stopped beam, delayed γ -ray decay experiments. Configuration for stopped beam experiments Energy [keV] 500 1000 1500 2000 2500 3000 FEP Efficiency / % 10 20 30 40 50 60 70 80 90 100 0 mm Al 0.5 mm Al 1. mm Al • 960 LaBr 3 detectors in a simple boxed shaped geometry, • 15 x 40 x 80 mm 3 crystal size • 12 cm distance to target, • Simulations performed with Al housings of 0, 0.5 and 1.0 mm thickness, • ≈ 85 % solid angle coverage, • High granularity is kept for high energetic γ-rays. Gamma Fold 0 2 4 6 8 10 12 Relative Intensity 1 10 2 10 3 10 4 10 500 keV 1000 keV 1500 keV 2000 keV 2500 keV 3000 keV Conclusions Configuration for fast beam experiments DALI2 array: 160 NaI detectors Energy [keV] 0 200 400 600 800 1000 1200 1400 1600 1800 2000 Counts / 10 keV 0 5 10 15 20 25 30 35 40 45 3 LaBr DALI2 Au 197 Sn*) 102 Sn, 102 Au( 197 Energy [keV] 500 1000 1500 2000 2500 3000 FEP Efficiency / % 10 20 30 40 50 60 70 80 100 MeV/u 150 MeV/u 200 MeV/u 250 MeV/u Energy [keV] 500 1000 1500 2000 2500 3000 Energy Resolution (FWHM) / % 2 2.5 3 3.5 4 4.5 5 5.5 100 MeV/u 150 MeV/u 200 MeV/u 250 MeV/u Relativistic Coulomb excitation of 102 Sn • 25 particles per second 102 Sn beam 150 MeV/u at secondary target, • Secondary target thickness of 500 mg/cm 2 Au, •B(E2; 0 + → 2 + ) = 0.044 e 2 b 2 from shell model calculations * , • 5 days beam on target. Isomer spectroscopy at the limits * A. Banu et al., PRC 72, 061305(R) (2005) 130 Cd 1325 1864 1992 2130 8 + 4 + 2 + 0 + 6 + RI Beam Factory SRC BigRIPS Location of LaBr 3 array IRC • 50 implanted 130 Cd isomers. Objectives and considerations •Construct a 4π LaBr 3 fast beam γ-ray detection array of up to 1000 detectors with an optimized geometry for RIBF energies of v/c = 0.6, •Energy resolution of less than 3 % (FWHM) at E γ = 1332.5 keV and E beam = 100 MeV/u, • Full energy peak efficiency (FEP) of 40 %, •Simple detector geometry for a maximum of flexibility and to allow for an easy reconfiguration of the array for stopped beam experiments, •In the first instance, the uncompleted array can be used in addition to a modified DALI2 array*. * S. Takeuchi et al., RIKEN Acc. Rep. 36, 148 (2003) • 960 LaBr 3 detectors, • Arranged in a configuration that keeps the same Doppler broadening due to the detectors’ opening angle for all polar angles at v/c = 0.6, • 15 x 40 x 80 mm 3 crystal size, • Simulations are performed with a 0.5 mm thick Al housing. Beam direction ZeroDegree • The LaBr 3 array in a configuration of 960 detectors with the dimensions of 15 x 40 x 80 mm 3 fulfills the set requirements on energy resolution and photopeak efficiency at the relativistic secondary beam energies of the RIBF. • The high granularity and efficiency of the array make it a powerful tool to study γ-γ angular correlations. • Only few implanted isomers are necessary to reconstruct level schemes. Therefore, the array is a dedicated equipment for the spectroscopy of very weakly produced isomers. Energy [keV] 0 200 400 600 800 1000 1200 1400 1600 1800 2000 Counts / 4 keV 0 2 4 6 8 10 12 14 16 18 20 22 > Gamma 0 200 400 600 800 1000 1200 1400 1600 < Gamma 0 100 200 300 400 500 600 0 0.5 1 1.5 2 2.5 3 3.5 4 γ-γ coincidences
Transcript of based -ray detection array for use at RIBF - · PDF fileA Novel LaBr 3 based -ray detection...
A Novel LaBr3 based γ-ray
detection array for use at RIBFP. Doornenbal1, H. Scheit1, N. Aoi1, T. Motobayashi1, H. Sakurai1, and S. Takeuchi1
1RIKEN Nishina Center for Accelerator-Based Science, 2-1 Hirosawa, Wako, Saitama 0351 - 0106, Japan
Motivation
Simulated exemplary experiments
With the Radioactive Ion Beam Factory (RIBF) at RIKEN being on the cusp to deliver the worldʼs most intense RI beams at energies of several hundred MeV/u, a new γ-ray detection array is required to exploit the new experimental possibilities coming along with it. The material LaBr3(Ce) possesses an unprecedentedly high intrinsic energy resolution for scintillators of 2 % (FWHM) at 1332.5 keV and an excellent time resolution below 500 ps and is therefore well suited for high-resolution in-beam γ-ray experiments at relativistic energies. To minimize Doppler effects, the total array will comprise of up to one thousand individual crystals. The array will be placed around the secondary target area of the large acceptance fragment separator BigRIPS. Alternatively, the array can be used in a different configuration for stopped beam, delayed γ-ray decay experiments.
Configuration for stopped beam experiments
Energy [keV]500 1000 1500 2000 2500 3000
FEP
Effic
ienc
y / %
10
20
30
40
50
60
70
80
90
1000 mm Al
0.5 mm Al
1. mm Al
• 960 LaBr3 detectors in a simple boxed shaped geometry,
• 15 x 40 x 80 mm3 crystal size• 12 cm distance to target,• Simulations performed with Al
housings of 0, 0.5 and 1.0 mm thickness,
• ≈ 85 % solid angle coverage,• High granularity is kept for high
energetic γ-rays.
Gamma Fold0 2 4 6 8 10 12
Rela
tive
Inte
nsity
1
10
210
310
410
500 keV1000 keV1500 keV2000 keV2500 keV3000 keV
Conclusions
Configuration for fast beam experiments
DALI2 array: 160 NaI detectors
Energy [keV]0 200 400 600 800 1000 1200 1400 1600 1800 2000
Coun
ts /
10 k
eV
0
5
10
15
20
25
30
35
40
453LaBr
DALI2Au197Sn*)102Sn,102Au(197
Energy [keV]500 1000 1500 2000 2500 3000
FEP
Effic
ienc
y / %
10
20
30
40
50
60
70
80100 MeV/u
150 MeV/u
200 MeV/u
250 MeV/u
Energy [keV]500 1000 1500 2000 2500 3000
Ener
gy R
esol
utio
n (F
WHM
) / %
2
2.5
3
3.5
4
4.5
5
5.5100 MeV/u
150 MeV/u
200 MeV/u
250 MeV/u
Relativistic Coulomb excitation of 102Sn
•25 particles per second 102Sn beam 150 MeV/u at secondary target,
•Secondary target thickness of 500 mg/cm2 Au,
•B(E2; 0+ → 2+) = 0.044 e2b2 from shell model calculations*,
•5 days beam on target.
Isomer spectroscopy at the limits
*A. Banu et al., PRC 72, 061305(R) (2005)
130Cd
1325
1864 1992 2130 8+
4+
2+
0+
6+
RI Beam Factory
SRC
BigRIPSLocation of LaBr3 array
IRC
•50 implanted 130Cd isomers.
Objectives and considerations•Construct a 4π LaBr3 fast beam γ-ray detection array of up to 1000 detectors with an optimized geometry for RIBF energies of v/c = 0.6,
•Energy resolution of less than 3 % (FWHM) at Eγ = 1332.5 keV and Ebeam = 100 MeV/u,
•Full energy peak efficiency (FEP) of 40 %,•Simple detector geometry for a maximum of flexibility and to allow for an easy reconfiguration of the array for stopped beam experiments,
•In the first instance, the uncompleted array can be used in addition to a modified DALI2 array*.
*S. Takeuchi et al., RIKEN Acc. Rep. 36, 148 (2003)
• 960 LaBr3 detectors,• Arranged in a configuration that
ke e p s t h e s a m e D o p p l e r broadening due to the detectors’ opening angle for all polar angles at v/c = 0.6,
• 15 x 40 x 80 mm3 crystal size,• Simulations are performed with a
0.5 mm thick Al housing.
Beam direction
ZeroDegree
•The LaBr3 array in a configuration of 960 detectors with the dimensions of 15 x 40 x 80 mm3 fulfills the set requirements on energy resolution and photopeak efficiency at the relativistic secondary beam energies of the RIBF.
•The high granularity and efficiency of the array make it a powerful tool to study γ-γ angular correlations.
•Only few implanted isomers are necessary to reconstruct level schemes. Therefore, the array is a dedicated equipment for the spectroscopy of very weakly produced isomers.
Energy [keV]0 200 400 600 800 1000 1200 1400 1600 1800 2000
Coun
ts /
4 ke
V
02468
10121416182022
>Gamma0 200 400 600 800 1000 1200 1400 1600
<Gam
ma
0
100
200
300
400
500
600
0
0.5
1
1.5
2
2.5
3
3.5
4γ-γ coincidences
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