A broadband gamma-ray spectrometry using novel unfolding algorithms for characterization of laser wakefield-generated betatron radiation

Journal Article · Tue Dec 15 00:00:00 EST 2015 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.4939014· OSTI ID:22482636

Nakajima, Kazuhisa; Pathak, Vishwa Bandhu; Cho, Myung Hoon; Yoo, Byung Ju; Shin, Kang Woo ^[1]; Kim, Hyung Taek; Sung, Jae Hee; Lee, Seung Ku; Choi, Il Woo ^[1]; Rhee, Yong Joo ^[2]; Shin, Jung Hun; Jo, Sung Ha ^[3]; Hojbota, Calin; Cho, Byeoung Ick; Nam, Chang Hee ^[1]

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1. Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 500-712 (Korea, Republic of)
2. Nuclear Data Center, Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of)
3. Advanced Photonics Research Institute, GIST, Gwangju 500-712 (Korea, Republic of)

We present a high-flux, broadband gamma-ray spectrometry capable of characterizing the betatron radiation spectrum over the photon energy range from 10 keV to 20 MeV with respect to the peak photon energy, spectral bandwidth, and unique discrimination from background radiations, using a differential filtering spectrometer and the unfolding procedure based on the Monte Carlo code GEANT4. These properties are experimentally verified by measuring betatron radiation from a cm-scale laser wakefield accelerator (LWFA) driven by a 1-PW laser, using a differential filtering spectrometer consisting of a 15-filter and image plate stack. The gamma-ray spectra were derived by unfolding the photostimulated luminescence (PSL) values recorded on the image plates, using the spectrometer response matrix modeled with the Monte Carlo code GEANT4. The accuracy of unfolded betatron radiation spectra was assessed by unfolding the test PSL data simulated with GEANT4, showing an ambiguity of less than 20% and clear discrimination from the background radiation with less than 10%. The spectral analysis of betatron radiation from laser wakefield-accelerated electron beams with energies up to 3 GeV revealed radiation spectra characterized by synchrotron radiation with the critical photon energy up to 7 MeV. The gamma-ray spectrometer and unfolding method presented here facilitate an in-depth understanding of betatron radiation from LWFA process and a novel radiation source of high-quality photon beams in the MeV regime.

• OSTI ID: 22482636
• Journal Information: Review of Scientific Instruments, Vol. 86, Issue 12; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
BACKGROUND RADIATION
BETATRONS
ELECTRON BEAMS
GAMMA SPECTRA
GAMMA SPECTROMETERS
GAMMA SPECTROSCOPY
GEV RANGE 01-10
KEV RANGE
LASERS
MEV RANGE 10-100
MONTE CARLO METHOD
PHOTOLUMINESCENCE
PHOTONS
SYNCHROTRON RADIATION
WAKEFIELD ACCELERATORS