title: A broadband gamma-ray spectrometry using novel unfolding algorithms for characterization of laser wakefield-generated betatron radiation.
abstract: 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.
authors.affiliation: Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 500-712, South Korea.
authors.forename: Jong Ho
authors.initials: JH
authors.lastname: Jeon
authors.affiliation: Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 500-712, South Korea.
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Nakajima
authors.affiliation: Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 500-712, South Korea.
authors.forename: Hyung Taek
authors.initials: HT
authors.lastname: Kim
authors.affiliation: Nuclear Data Center, Korea Atomic Energy Research Institute, Daejeon 305-353, South Korea.
authors.forename: Yong Joo
authors.initials: YJ
authors.lastname: Rhee
authors.affiliation: Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 500-712, South Korea.
authors.forename: Vishwa Bandhu
authors.initials: VB
authors.lastname: Pathak
authors.affiliation: Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 500-712, South Korea.
authors.forename: Myung Hoon
authors.initials: MH
authors.lastname: Cho
authors.affiliation: Advanced Photonics Research Institute, GIST, Gwangju 500-712, South Korea.
authors.forename: Jung Hun
authors.initials: JH
authors.lastname: Shin
authors.affiliation: Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 500-712, South Korea.
authors.forename: Byung Ju
authors.initials: BJ
authors.lastname: Yoo
authors.affiliation: Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 500-712, South Korea.
authors.forename: Calin
authors.initials: C
authors.lastname: Hojbota
authors.affiliation: Advanced Photonics Research Institute, GIST, Gwangju 500-712, South Korea.
authors.forename: Sung Ha
authors.initials: SH
authors.lastname: Jo
authors.affiliation: Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 500-712, South Korea.
authors.forename: Kang Woo
authors.initials: KW
authors.lastname: Shin
authors.affiliation: Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 500-712, South Korea.
authors.forename: Jae Hee
authors.initials: JH
authors.lastname: Sung
authors.affiliation: Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 500-712, South Korea.
authors.forename: Seung Ku
authors.initials: SK
authors.lastname: Lee
authors.affiliation: Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 500-712, South Korea.
authors.forename: Byeoung Ick
authors.initials: BI
authors.lastname: Cho
authors.affiliation: Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 500-712, South Korea.
authors.forename: Il Woo
authors.initials: IW
authors.lastname: Choi
authors.affiliation: Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 500-712, South Korea.
authors.forename: Chang Hee
authors.initials: CH
authors.lastname: Nam