RIKEN, Wako
A highly sensitive beam current monitor with an HTS (High-Temperature Superconducting) SQUID (Superconducting QUantum Interference Device) and an HTS current sensor, that is, an HTS SQUID monitor, has been developed for use of the RIBF (RI beam factory) at RIKEN. Unlike other existing facilities, the HTS SQUID monitor allows us to measure the DC of high-energy heavy-ion beams nondestructively in real time, and the beam current extracted from the cyclotron can be recorded without interrupting the beam user's experiments. Both the HTS magnetic shield and the HTS current sensor were dip-coated to form a Bi2 - Sr2 - Ca2 - Cu3 - Ox (Bi-2223) layer on 99.9 % MgO ceramic substrates. In the present work, all the fabricated HTS devices are cooled by a low-vibration pulse-tube refrigerator. These technologies enabled us to downsize the system. Prior to practical use at the RIBF, the HTS-SQUID monitor was installed in the beam transport line of the RIKEN ring cyclotron to demonstrate its performance. As a result, a 20 μA 40Ar15+ beam intensity (63 MeV/u) was successfully measured with a 500 nA resolution. Despite the performance taking place in an environment with strong gamma ray and neutron flux radiations, RF background and large stray magnetic fields, the measurements were successfully carried out in this study. This year, the HTS SQUID monitor was upgraded to have aresolution of 100 nA and was reinstalled inthe beam transport line, enabling us to measure a 4 μA 132Xe20+ (10.8 MeV/u) beam and a 1 μA 132Xe41+ (50.1 MeV/u) beam used for the accelerator operations at RIBF. Hence, we will report the results of the beam measurements an the present status of the HTS SQUID monitor.
GSI, Darmstadt
ITEP, Moscow
In the frame of the FAIR project in spring 2008 an irradiation test of superconducting magnet components was done at GSI Darmstadt. Cave HHD with the beam dump of SIS18 synchrotron was taken as the test area. The beam dump was reequipped to meet the irradiation test requirements. Thereby the first stage of preparation for the irradiation test was to investigate the radiation field around the reconstructed beam dump from the point of view of radiation safety. FLUKA simulations were performed to estimate the dose rate inside and immediate outside of the cave during the irradiation. The simulations showed safe level of the radiation field, and it was later confirmed by the measurements provided by the radiation safety group of GSI.
GSI, Darmstadt
Funding: Work is partially supported by project VEGA 1/0129/09.
In the frame of the FAIR project irradiation test of superconducting magnet components was performed at GSI Darmstadt in May 2008. As a part of the experiment stainless steel samples were irradiated by 1 GeV/u 238U ions. In contrast to the previous experimental studies performed with thick cylindrical samples, the target was a thin plate irradiated at small angle. The target was constituted as a set of individual foils. This stacked-foil target configuration was foreseen for depth-profiling of residual activity. Gamma-ray spectroscopy was used as the main analytical technique. The isotopes with dominating contribution to the residual activity induced in the samples were identified and their contributions were quantified. Depth-profiling of the residual activity of all identified isotopes was performed by measurements of the individual target foils. The characteristic shape of the depth-profiles for the products of target activation and projectile fragments was found and described. Monte Carlo code FLUKA was used for simulations of the residual activity and for estimation of the number of ions delivered to the target and their distribution. The measured data are relevant for assessment of radiation situation at high-energy accelerators during the “hands-on” maintenance as well for assessment of the tolerable beam-losses.
JINR, Dubna
Accelerated heavy ions get a charge spectrum on passing a thing target. The charge dispersion and its maximum depend on the ion type, its energy, material, and the foil thickness. Change of the ion charge leads to change of the ion magnetic rigidity. Heavy ion beam extraction from the AVF cyclotrons by stripping in the thing targets is based on loss of the radial stability of the accelerated beam after its magnetic rigidity change. Property data of carbon foils used for the heavy ion beam extraction by stripping are given. Experience of using heavy ion beam extraction from the AVF cyclotrons of FLNR (Dubna) by stripping is considered.
CNRS/IN2P3, Strasbourg
This second generation radioactive ion beam facility will be constructed at GANIL and be operational in 2012 with stable beams and 2013 with radioactive ion beams. The aim of the installation is to produce high-intensity, high-quality radioactive ion beams of isotopes from large regions of the chart of nuclei in the range of 3 to 240u. Following description corresponds to the conceptual design study of a low energy RIB transport line for the SPIRAL 2 project.
GANIL, Caen
For the GANIL safety revaluation and the new project of accelerator SPIRAL 2, it was decided to replace the existing access control system for radiological controlled areas. These areas are all cyclotron rooms and experimental areas. The existing system is centralized around VME cards. Updating is becoming very problematic. The new UGA (access control unit) will be composed of a pair of PLC to ensure the safety of each room. It will be supplemented by a system UGB (radiological control unit) that will assure the radiological monitoring of the area concerned. This package will forbid access to a room where the radiological conditions are not sure and, conversely, will forbid the beam if there is a possibility of presence of a person. The study of the system is finished and the record of safety in preparation. At GANIL, the ions are accelerated by cyclotrons (C01 or C02, CSS1, CSS2, CIME) and are transported through beamlines towards the rooms of experiments (D1-D6, G1-G4). A first named extension SPIRAL was brought into service in 2000. It makes it possible to produce and post-accelerate, via the cyclotron CIME, the radioactive ion beams obtained by fragmentation of stable ions resulting from CSS2 in a carbon target. The project SPIRAL2 will arrive soon and has the same need in safety. Each room must thus remain confined (without human presence) when potentially dangerous ionizing radiations are present. This protection was identified as an important function for safety and is provided by EIS (Important Equipment for Safety). The EIS of GANIL are referred and described in the RGE (General Rules of Exploitation). It was decided to replace the current systems of security management by four distinct but interconnected systems.