RADIATION MEASUREMENT IN THE 1ST BEAM COMMISSIONING CAMPAIGN OF THE LIPAc RFQ K. Kondo, S. Kwon, T. Shinya, M. Sugimoto, K. Sakamoto, QST, Rokkasho, Aomori, Japan L. Bellan, F. Grespan, F. Scantamburlo, INFN/LNL, Legnaro, Italy I. Podadera, CIEMAT, Madrid, Spain H. Dzitko, R. Heidinger, Fusion for Energy, Garching, Germany P. Cara, IFMIF/EVEDA Project Team, Rokkasho, Aomori, Japan Abstract The 1st proton beam acceleration of the Linear IFMIF Prototype Accelerator (LIPAc) through its novel RFQ was succeeded on 13th June 2018. Addition to plenty of beam diagnostics equipped in the beam line, we prepared some radiation detectors placed around the accelerator in order to acquire supplemental information of the beam, as an in- direct measurement. In the first day of the beam injection to the RFQ, the gamma-rays corresponding to certain ex- cited states of Al of the low power beam dump were suc- cessfully detected by a LaBr3(Ce) scintillation detector. Some neutrons, which would originate from the interaction of protons with Cu somewhere, were also observed. These results proved that the beam was certainly accelerated up to about 2.5 MeV, and provided us a definitive confidence that the RFQ was working appropriately from the very be- ginning of the commissioning. Also, the comparison of the radiation yields with the RFQ transmission provided addi- tional information on the beam energy distribution. INTRODUCTION The construction of the Linear IFMIF Prototype Accel- erator (LIPAc), which is a prototype of the IFMIF (Interna- tional Fusion Material Irradiation Facility) deuteron accel- erator projected to validate the acceleration of deuterons up to 9 MeV with a beam current of 125 mA in CW, is pro- gressing at Rokkasho, Aomori, Japan [1]. The beam com- missioning of LIPAc is now in the stage of ‘Phase-B’, in which we aim to have deuteron beam acceleration up to 5.0 MeV through the novel RFQ [2] and the characterization of the beam in pulsed mode at low duty cycle (0.1% in nominal) [3]. Also, the commissioning of MEBT section with two bunchers [4], as an interface to the SRF Linac, and the functionality test of beam diagnostics are ongoing. The 1st proton beam acceleration of the LIPAc through the RFQ was succeeded on 13th June 2018 [5]. Addition to plenty of beam diagnostics equipped in the beam line, we prepared some radiation detectors placed around the accel- erator in order to acquire supplemental information of the beam, as an indirect measurement. The details of the at- tempt of this measurement are presented in this paper. The comparison of the radiation yield with the RFQ transmis- sion measurement is discussed as well. LIPAc PHASE-B CONFIGURATION Figure 1 shows the accelerator layout of LIPAc in Phase-B. The accelerator consists of the injector with an ECR ion source (H + 50 keV/ D + 100 keV), LEBT, then the world longest RFQ, MEBT composed of 5 Q magnets, 2 scrapers and 2 bunchers, D-Plate and the low power beam dump (LPBD) that can withstand only low duty cycle op- erations. LPBD consists of an aluminium alloy cone that is water-cooled, lead gamma shields and polyethylene neu- tron shields surrounding the cone. While the final goal of the Phase-B is the demonstra- tion of the 125 mA deuteron acceleration to 5 MeV with pulsed beam of 1 ms, 1 Hz (duty 0.1%), the initial beam commissioning was started with proton beam (2.5 MeV at the exit of RFQ) with a smaller current around 10 mA, which was the achievable minimum with the LIPAc ion source. The pulse width injected to RFQ was set to 300 s by using a chopper in LEBT. As the beam diagnostics, three ACCTs placed at the entrance of RFQ, the exit of RFQ, on the D-Plate and 7 sets of BPM (4 in MEBT and 3 in D-Plate) [6] were available from the beginning as well as LPBD, whose cone was isolated and used as Faraday Cup. Figure 1: Layout of LIPAc in Phase-B. RADIATION MEASUREMENT PRINCIPLE Gamma-rays from LPBD The threshold energy of the 27 Al(p,n) reaction is 5.80 MeV, thus no neutrons are produced on LPBD. Several specific gamma rays can be produced from the inelastic scattering of proton on Al. The following three lines are expected to be dominant with the proton beam of 2.5 MeV [7]: 844 keV : 27 Al(p,p’ 1 ) 1014 keV : 27 Al(p,p’ 2 ) 10th Int. Particle Accelerator Conf. IPAC2019, Melbourne, Australia JACoW Publishing ISBN: 978-3-95450-208-0 doi:10.18429/JACoW-IPAC2019-MOPTS047 MOPTS047 964 Content from this work may be used under the terms of the CC BY 3.0 licence (© 2019). Any distribution of this work must maintain attribution to the author(s), title of the work, publisher, and DOI MC4: Hadron Accelerators A08 Linear Accelerators