II. Physical Aspects of the Fast Neutron Beam

Abstract

The neutrons are generated by accelerating a beam of deuterons to 15 MeV in the M.R.C. 45 in. Cyclotron (Gallop, Vonberg, Post, Powell, Sharp and Waterton, 1957). A fraction of the beam is extracted from between the dees and falls on an external target consisting of a thick sheet of beryllium (the thickness of the target was 290 mg/cm2, the range of the deuterons being 180 mg/cm2). From here neutrons radiate in all directions, being most intense in the forward direction. The M.R.C. cyclotron was designed to give a large beam current and to run with the greatest possible degree of reliability. It performs well, giving about 50 μA at the external target for long periods of time. Figure 1 is a general view of the machine as it was several years ago, before the external target had been added. Figure 2 is a plan view of the cyclotron chamber. Neutrons are shown emerging from the target and crossing the space where the radiobiological experiments were performed. The cyclotron team is at present modifying the machine to provide a remote neutron target at a depth in the concrete wall. Figure 3 shows this together with the new irradiation room. The modification will make it possible to treat patients in the adjoining room and will also make biological irradiations more convenient. The neutrons are generated by accelerating a beam of deuterons to 15 MeV in the M.R.C. 45 in. Cyclotron (Gallop, Vonberg, Post, Powell, Sharp and Waterton, 1957). A fraction of the beam is extracted from between the dees and falls on an external target consisting of a thick sheet of beryllium (the thickness of the target was 290 mg/cm2, the range of the deuterons being 180 mg/cm2). From here neutrons radiate in all directions, being most intense in the forward direction. The M.R.C. cyclotron was designed to give a large beam current and to run with the greatest possible degree of reliability. It performs well, giving about 50 μA at the external target for long periods of time. Figure 1 is a general view of the machine as it was several years ago, before the external target had been added. Figure 2 is a plan view of the cyclotron chamber. Neutrons are shown emerging from the target and crossing the space where the radiobiological experiments were performed. The cyclotron team is at present modifying the machine to provide a remote neutron target at a depth in the concrete wall. Figure 3 shows this together with the new irradiation room. The modification will make it possible to treat patients in the adjoining room and will also make biological irradiations more convenient.The neutrons are generated by accelerating a beam of deuterons to 15 MeV in the M.R.C. 45 in. Cyclotron (Gallop, Vonberg, Post, Powell, Sharp and Waterton, 1957). A fraction of the beam is extracted from between the dees and falls on an external target consisting of a thick sheet of beryllium (the thickness of the target was 290 mg/cm2, the range of the deuterons being 180 mg/cm2). From here neutrons radiate in all directions, being most intense in the forward direction. The M.R.C. cyclotron was designed to give a large beam current and to run with the greatest possible degree of reliability. It performs well, giving about 50 μA at the external target for long periods of time. Figure 1 is a general view of the machine as it was several years ago, before the external target had been added. Figure 2 is a plan view of the cyclotron chamber. Neutrons are shown emerging from the target and crossing the space where the radiobiological experiments were performed. The cyclotron team is at present modifying the machine to provide a remote neutron target at a depth in the concrete wall. Figure 3 shows this together with the new irradiation room. The modification will make it possible to treat patients in the adjoining room and will also make biological irradiations more convenient.