Development of a detector for a two-dimensional type beam profile monitor with the use of high intensity beams

研制了一种二维束流剖面测量仪，成功地实现了束流剖面的无损测量。用于这些测试的束与用于NIRS HIMAC的注入束一起使用，其能量为6 MeV/u，脉冲持续时间为500至800微秒，并且碳、氧和氖的离子种类被完全剥离。束流强度为10的十一次方par脉冲量级。靶是氮气射流片，其厚度为2或5 mm，宽度为60 mm（扁平），密度为1 e-3 Pa。光束与氮片碰撞的作用，产生波长近400 nm的可见光发射，由下面的探测器探测。上述束流条件对应于与任何GeV级强流加速器作用的情况下的十分之一。探测器采用像增强器（II）和高增益摄像管（HARP）组成。通过对几十个脉冲进行平均测量，确认了光束轮廓。结果表明，采用高强度束流（设计强度：4 e13质子par束流）如J-PARC MR，在几束流时间内，束流轮廓将能够检测到。在设备研制中，以γ射线照射为总剂量为1 ~ 5 MGy，对II的辐射损伤点进行了检测，并将这些材料改为抗辐射材料。为了避免大气中氮气的辐射，将低损耗的探测光学系统安装在真空室中。光从II到HARP相机的传输是使用辐射硬度型成束图像光纤完成的。而II是由远程高压传输操作。

A tow-dimensional type beam profile monitor was developed, and beam profiles were successfully measured without destruction to beams. The beam for these tests were used with injection beams for NIRS HIMAC, of which energy of 6MeV/u, pulse duration of five to eight hundreds micro second, and ion species of carbon, oxygen, and neon with fully stripped. The beam intensity was an order of 10 to the eleventh par pulse. The target was a nitrogen gas jet sheet, of which thickness of 2 or 5mm, width of 60mm (flattened), and density of le-3 Pa. The action of collision between beam and nitrogen sheet, visible light emission of which wave length of almost 400nm is occurred, and which is detected by below detector. Above beam conditions was corresponding to one-tenth in the case of the beam action with any high intensity accelerator of GeV class. The detector was employed an image intensifier (II) and high gain video camera consists of pickup tube (HARP). Beam profiles were confirmed measuring with several ten pulses averaging. This results shows that with high intensity beams (design intensity: 4e13 proton par bunch) such as J-PARC MR, within a time of several bunch, beam profile will be able to detect.In equipment developments, with gamma ray exposure as total dose was 1 to 5MGy, II' s radiation weal points were examined, and the these materials were changed to radiation hardness materials. Avoiding to an emission of light by nitrogen in atmosphere, detection optics with low loss was set in a vacuum chamber. Light transportation from II to HARP camera was done using a radiation hardness type bundled image fibers. And II was operated by remote high voltage transfer.