A very compact inverse Compton scattering gamma-ray source

Yingchao Du; Han Chen; Hongze Zhang; Qiang Gao; Qili Tian; Zhijun Chi; Zhi Zhang; Hao Zha; Jiaru Shi; Lixin Yan; Rui Qiu; Cheng Cheng; Taibin Du; Renkai Li; Huaibi Chen; Wenhui Huang; Chuanxiang Tang

doi:10.11884/HPLPB202234.220132

Journals >High Power Laser and Particle Beams >Volume 34 >Issue 10 >Page 104010 > Article

High Power Laser and Particle Beams
Vol. 34, Issue 10, 104010 (2022)

A very compact inverse Compton scattering gamma-ray source

Yingchao Du¹, Han Chen¹, Hongze Zhang¹, Qiang Gao¹, Qili Tian¹, Zhijun Chi², Zhi Zhang¹, Hao Zha¹, Jiaru Shi¹, Lixin Yan¹, Rui Qiu¹, Cheng Cheng¹, Taibin Du¹, Renkai Li¹, Huaibi Chen¹, Wenhui Huang¹, and Chuanxiang Tang^1、*

Author Affiliations

¹Department of Engineering Physics, Tsinghua University, Beijing 100084, China

²College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875, China

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DOI: 10.11884/HPLPB202234.220132 Cite this Article

Yingchao Du, Han Chen, Hongze Zhang, Qiang Gao, Qili Tian, Zhijun Chi, Zhi Zhang, Hao Zha, Jiaru Shi, Lixin Yan, Rui Qiu, Cheng Cheng, Taibin Du, Renkai Li, Huaibi Chen, Wenhui Huang, Chuanxiang Tang. A very compact inverse Compton scattering gamma-ray source[J]. High Power Laser and Particle Beams, 2022, 34(10): 104010 Copy Citation Text

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Fig. 1. Schematic diagram of the very compact inverse Compton scattering gamma-ray source (VIGAS)

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Fig. 2. Layout of the accelerator in VIGAS

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Fig. 3. Relation between bunch length and emittance plus energy spread after optimization

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Fig. 4. Pareto front of emittance and bunch length with 200 pC bunch charge and 500 pC bunch charge

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Fig. 5. Beam dynamics simulation results in the case of 200 pC bunch charge

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Fig. 6. Bunch energy and emittance versus the ratio of acceleration gradient

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Fig. 7. Photon energy versus the ratio of acceleration gradient

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Fig. 8. Block diagram of driving laser shaping design

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Fig. 9. Block diagram of scattering laser design

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Fig. 10. Simulated photon yield at different photon energy

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Fig. 11. Photon bandwidth and the proportion within the collection angle versus the collection angle

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Fig. 12. Photon spectroscopy within different collection angles using 800 nm scattering laser

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Fig. 13. Photon spectroscopy within different collection angles using 400 nm scattering laser

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Fig. 14. Photon spectroscopy in simulation taking jitter into consideration

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parameter	value
γ ray photon energy	continuously adjustable between 0.2～4.8 MeV
relative bandwidth (RMS)/%	＜1.5 (after collimation)
photon yield/(photons·s⁻¹)	＞4.0×10⁸@0.2～2.4 MeV；＞1.0×10⁸@2.4～4.8 MeV
photon yield within 1.5% bandwidth	＞4.0×10⁶@0.2～2.4 MeV; ＞1.0×10⁶@2.4～4.8 MeV
degree of polarization	adjustable from linear to circular polarization

Table 1. Performance parameters of VIGAS

parameter	value
bunch energy/MeV	50～350
bunch charge/pC	＞200
normalized emittance/(mm·mrad)	＜0.6
bunch length/ps	＜2
energy spread/%	＜0.3
focused spot size/µm	＜20
repetition rate/Hz	10

Table 2. Parameters of electron beam in VIGAS

parameter	value
parameter	800 nm	400 nm
bandwidth/nm	＜15	＜8
pulse energy/J	＞1.5	＞0.8
pulse length (FWHM)/ps	＜10
focused spot size (RMS)/μm	＜10

Table 3. Parameters of scattering laser in VIGAS

parameters	range	optimization result
parameters	range	200 pC	500 pC
laser duration/ps	[4, 20]	7.27	7.09
laser beam size (RMS)/mm	[0.2, 2]	0.2	0.33
launch phase/(°)	[−20, 20]	5.4	3.0
gun solenoid strength/T	[0.15, 0.35]	0.2024	0.2018
gun solenoid center/m	[0.213 7, 0.213 7]	0.2137	0.2137
buncher field strength/(MV·m⁻¹)	[20, 50]	36.1	43.4
buncher center/m	[0.73, 0.9]	0.9665	0.9665
buncher phase/(°)	[−110, −80]	−100	−98.5
linac center/m	[1.5, 2]	2.402	2.402
linac solenoid center/m	[1.5, 2]	1.6	1.6
linac solenoid strength/T	[0, 0.2]	0.0804	0.109

Table 4. Variable parameters in the optimization

normalized emittance/(μm·rad)	bunch length (RMS)/mm	bunch energy/MeV	energy spread (RMS)/MeV	bunch charge/pC
0.294	0.208	361.3	0.45	200
0.623	0.202	361.5	0.40	500

Table 5. Optimized beam parameters with 200 pC bunch charge and 500 pC bunch charge

parameters	value
central wavelength/nm	267
repetition rate/Hz	10
pulse energy/μJ	2～500
pulse width (FWHM)/ps	5-10
rising and falling edge (10%～90%)/ps	1.0
beam size (RMS)/mm	0.2～2
energy jitter (RMS)/%	＜2.0
time jitter between RF and laser (RMS)/ps	＜0.1

Table 6. Parameters of the driving laser system

parameters	jitter range
bunch charge/%	$ \pm 2 $
laser duration/%	$ \pm 2 $
laser beam size/%	$ \pm 2 $
gun field strength/%	$ \pm 0.1 $
gun phase	$ \pm 0.5 $
buncher field strength/%	$ \pm 0.1 $
buncher phase	$ \pm 0.5 $
S band linac field strength/%	$ \pm 0.1$
S band linac phase	$ \pm 0.5 $
X band linac field strength/%	$ \pm 0.1 $
X band linac phase	$ \pm 1 $
scattering laser pulse energy/%	$ \pm 2$
relative position between electron and laser beam/μm	$ \pm 3 $
arrival time/ps	$ \pm 0.25 $

Table 7. Parameter jitter range in the joint parameter sweep

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