Prompt In-Line Diagnosis of Single Bunch Transverse Profiles and Energy Spectra for Laser-Accelerated Ions Hironao Sakaki  , Mamiko Nishiuchi, Toshihiko Hori, Paul R. Bolton, Akifmi Yogo, Masaki Katagiri, Kouichi Ogura, Akito Sagisaka, Alexander S. Pirozhkov, Satoshi Orimo, Kiminori Kondo, Hiroshi Iwase 1 , Koji Niita 2 , Hikaru Souda 3 , Akira Noda 3 , Yasushi Iseki 4 , and Takeshi Yoshiyuki 4 Japan Atomic Energy Agency, Kizugawa, Kyoto 619-0215, Japan 1 KEK, Tsukuba, Ibaraki 305-0801, Japan 2 Research Organization for Information Science & Technology, Tokai, Ibaraki 319-1106, Japan 3 Kyoto University, Uji, Kyoto 611-0011, Japan 4 TOSHIBA Corp., Power Systems Company, Minato, Tokyo 105-8001, Japan Received October 5, 2010; accepted November 2, 2010; published online November 26, 2010 Many applications of laser-accelerated ions will require beamlines with diagnostic capability for validating simulations and machine performance at the single bunch level as well as for the development of controls to optimize machine performance. We demonstrated prompt, in-line, single bunch transverse profile and energy spectrum detection using a thin luminescent diagnostic and scintillator-based time-of-flight spectrometer simultaneously. The Monte Carlo code, particle and heavy ion transport code systems (PHITS) simulation is shown to be reasonably predictive at low proton energy for the observed transverse profiles measured by the thin luminescent monitor and also for single bunch energy spectra measured by time-of-flight spectrometry. # 2010 The Japan Society of Applied Physics DOI: 10.1143/APEX.3.126401 O ngoing studies of the laser-acceleration of ions reveal increased target diversity 1) and sophistica- tion and also mandate the timely development of adequate instrumentation for diagnostics, monitoring and control of beamlines developed with these sources. In particular, applications to laser-driven ion beam radio- therapy (L-IBRT) 2) will demand stringent beam monitor and control requirements for highly localized and safe irradiation of affected tissue. Understanding the origin and extent of source instability is essential for the safe irradiation of single shots. So, the performance optimization of laser-driven accelerators for L-IBRT requires companion development of instrumenta- tion that is suitable for the high peak current and short bunch duration that are typical of the laser-driven case. To experimentally assess pointing and spectral instabilities we measure single bunch (for a single laser shot) transverse beam profiles and energy spectra at key locations along a laser-driven proton beamline that is comprised of permanent magnet quadrupoles (PMQs). 3) For laser-accelerated ion studies, mostly of protons to date, use of the scintillator- based time-of-flight (TOF) spectrometer to measure energy spectra is typically combined with a solid track detector (CR39) or the imaging plate to measure the transverse beam profile. The solid track detector is not prompt and requires postprocessing, an etching procedure that can take at least 30 min following a measurement. Interpretation of CR39 data requires that the dose level to which this detector is exposed and the subsequent etching procedure that reveals pitting must be well controlled. 4) Using a short test beamline we report our results from real-time (prompt in-line) diagnosis of single proton bunches measuring energy spectra by TOF spectrometry 5) and transverse beam profiles using a thin luminescent single bunch profile monitor (LSBPM). The TOF spectrometer is composed of a circular thin plastic scintillator and a photomultiplier tube. In the present experimental setup, the plastic scintillator was covered with an aluminum sheet of thickness 1.0 mm with a central aperture of 10.0 mm diameter (the measurement solid angle is 9:04  10 3 msr at 2947 mm). The energy resolution of the TOF spectrometer is 50:0 keV for 1.0 MeV protons. The TOF spectrometer and LSBPM were tested with a beam focused by a triplet of PMQs as illustrated in Fig. 1. The J-KAREN 6) laser system at JAEA provided P-polarized laser irradiation at a 45.0  incident angle with laser pulses of a central wavelength of 800 nm, duration of 45.0 fs (full width at half maximum), and energy of 630 mJ at a 1 Hz repetition rate. The laser target (proton source) was a polyimide tape of 12.0 m thickness. Peak irradiances up to 10 19 W/cm 2 were achieved on target and the intensity contrast ratio was set to 10 10 . This contrast is defined to be the ratio of the intensity of a prepulse, which is generated in a few seconds before the main pulse, to that of the main pulse. Located 863 mm from the tape source the LSBPM measured transverse profiles of single proton bunches at different energies determined by upstream aluminum filters, with thicknesses of 12.5, 25.0, and 40.0 m, as shown in Fig. 2. The TOF unit was placed further at 2947 mm from the tape source with the LSBPM in this configuration. Silver activated zinc sulfide, ZnS(Ag), powder is typically used for neutron measurement 7) and has been adopted as the Acrylic window (3cm thickness) CCD camera TOF spectrometer LSBPM Proton beam PMQ triplet Tape target Laser beam 2947mm 863mm 1st 2nd 3rd Fig. 1. Transport optics for the LSBPM test beamline. For the permanent magnet quadrupole (PMQ) triplet, the first PMQ is 55.0 T/m (50.0 mm length) and 79:5  0:5 mm from laser irradiation point, the second is 40:0 T/m (50.0 mm length) and 128:5  0:5 mm from the first and the third is 60.0 T/m (20.0 mm length) and 89:3  0:5 mm from the second.  E-mail address: sakaki.hironao@jaea.go.jp Applied Physics Express 3 (2010) 126401 126401-1 # 2010 The Japan Society of Applied Physics