Study of High-Energy Nuclear-Beam Transport

对高能重离子束输运技术在国内外各种加速器设施上的研究现状进行了综述。与重离子输运有关的基本问题，即(1)与质子束相比强度相对很低；(2)弹丸破片造成的瞬时光束损失；(3)由于破碎产物的质子/中子比与原色相同，导致束流纯度下降；被发现是那里的常见问题。CERN、BNL和GSI为重离子输运开发了几种非常人工的光束轮廓/强度/位置监测仪。这些都是非常灵敏的光束探测器，可以分辨入射高能粒子的原子序数。我们还发现，低能设施的束流监测器可以应用于高能重离子束流。电子束监测仪的发展在不久的将来也引起了人们对脉冲束的关注。这些监测仪的图纸被系统地收集并保存在KEK-PS的波束通道组。重离子强度的绝对定标是重离子强度的重要技术之一。目前尚无标准方法。BNL和CERN的工作人员使用离子室，用低强度质子对其进行校准，并利用dE/dx-z^2推断出光束强度/输出电流与重离子的关系；其中z是主粒子的原子序数。假设高z原色离子室的线性响应是默认的。不幸的是，这是一个错误。然后我们关注目标碎片化过程。即使在重离子诱导反应中，靶碎片的生成截面也得到了很好的确定。然后，我们可以通过测量目标碎片中发射的具有适当原子序数的中间质量碎片（IMFs）的数量来确定初生重离子的强度。我们采用Bragg曲线计数器（BCC）作为IMF检测器，可以同时测定IMF si的原子序数和能量。我们建造了BCC的原型，并在日本进行了测试。这项工作的一部分已在几篇期刊文章中发表。在研究过程中，我们发现重离子束输运技术与加速器设备的物理方案密切相关。然后，我们将研究部分扩展到使用重离子束的物理程序。这一研究结果也在KEK的波束通道组中积累起来。少

Present status of the high-energy heavy-ion beam transport technology was investigated at various accelerator facilities in the world.Basic problems associated with the heavy-ion transport, i.e. (1) Relatively very low intensity compared with the proton beam ; (2) Immediate beam loss through the projectile fragmentation ; (3) Beam purity deterioration due to the fragmentation products of the same proton/neutron ratio as primaries ; were found to be the common problems there. Several very artificial beam profile/intensity/position monitors were developed for the heavy-ion transport at CERN,BNL,and GSI.These are all very keen beam detectors and can discriminate atomic numbers of the incoming high energy particle. We found also that beam monitors at low energy facilities can be applied for the high-energy heavy-ion beam. Beam monitors developed for electron beam were also interesting for the pulsed beam in near future. Drawings of these monitors were systematically collected and kept at t … More he beam channel group of the KEK-PS.The absolute calibration of the heavy-ion intensity is the one of the most important technology. At present no standard method is established. People at BNL and CERN employed the ion chamber and calibrated it by low intensity protons and extrapolated the beam-intensity/output-current relation to heavy ions using dE/dx-z^2 ; where z is the atomic number of the primary particle. The linear response of ion chamber for high-z primaries is tacitly assumed. It is, unfortunately, a fault. We then paid our attention to the target fragmentation process.The production cross sections of the target fragmentation are exceptionally well established even in the heavy-ion induced reactions. Then we can determine the primary heavy-ion intensity by measuring number of intermediate mass fragments (IMFs) with proper atomic number emitted in the target fragmentation. We employed the Bragg Curve Counter (BCC) as an IMF detector, which can determine the atomic number and energy of IMFs si, ultaneously. We constructed the prototype of the BCC and tested it in Japan. A part of this work has been published in several journal articles.During the investigation, we found that the heacy-ion beam transport technology is closely related with the physics program of the accelerator facility. We then partly extended our investigation to the physics program using heavy-ion beams. Results of this investigation is also accumulated at the beam channel group of the KEK. Less