Nuclear Instruments and Methods最新文献

Carbon stripper foils produced by vacuum evaporation were tested in the terminal of the MP-8 tandem accelerator. Conventionally floated and mounted foils served as standard stripper foils. Foils of the same kind were treated either by thermal radiation, electron bombardment of laser light (1.06 um) in order to modify their crystalline structure. Stripper lifetimes were determined as a function of type and thickness of the foils, beam current density, beam position on the foil and ion species. The special treatments of the foils prior to exposure to the beam resulted in considerably increased lifetimes. Foils of 5 um/cm² areal density treated by Nd:YAG laser light proved to be best and showed lifetimes increased by a factor 10 on the average as compared to standard foils.

The laws of beam dynamics governing the weak beam transport in a six-dimensional geometric phase-space and in the appropriate higher-order phase-space are proven by means of the statistics, and the general equations of motion of the higher-order envelope matrix are derived.

The 12 UD Pelletron installed at the Tandem Accelerator Center of the University of Tsukuba has been in operation for nearly four years. The installation of the accelerator is described and the operational experience with the accelerator and associate facilities are summarized.

A review is given of production methods, irradiation behaviour and lifetime and some physical characteristics of glow discharge foils prepared and tested at a number of laboratories. Results are summarised of hydrogen content determinations and of crystallographic studies of irradiated and non-irradiated materials.

Presently a computer monitor and control system for the Munich MP tandem accelerator is being developed. It is based on a PDP-11/34 with disc units, DEC-tapes, and an interactive graphic terminal. The accelerator is connected to the system via CAMAC hardware. A monitor program takes all data and stores the accelerator status in the memory and in a direct access file. A logbook file is created and the logbook is printed. During test-runs subsystems of the accelerator have been controlled. A beam transport program controlling a quadrupole doublet and optimizing the beam current measured at a Faraday cup was operated successfully.

A picosecond bunching system has been installed at the Munich MP tandem accelerator. The performance of the system was tested with heavy ions. Time resolutions as low as 50 ps (fwhm) for ¹⁶O were achieved with Si-surface barrier detectors. Examples of the mass resolution of reaction products from heavy ion induced reactions are given.

Since the Ebeltoft meeting, the MP-10 has run essentially for research at normal running specifications up to 13 MV for the first year. The belt is still a standard HVEC belt but mounted in a half open structure. It has accumulated more than 9000 h. Since August 1979, the time has been mainly devoted to our up-grading project and problems associated with this.

An outline is given of the Orsay project for a tandem postaccelerator

A report on the present status of the XTU tandem installation in Legnaro (Padova) is presented. The building and the technical and electric plants are almost completed. The 150 kV injector has been preliminary tested with a sputter source for ¹²C, ³²S, and ⁶³Cu negative ions. The SF₆ gas handling system (gaseous phase storing) has been completely installed and tested. The laddertron charging system was able to deliver 400 uA per chain (up charge + down charge) according to the specifications. The column structure has been successfully tested up to 20 MV, as guaranteed, with +7.3 bar pure SF₆ and −55°C dew point. The accelerator tubes have therefore been installed and will be tested in November 1980. The beam transport provided by standard HVEC high energy extension, a 90° analyzing magnet (B_ϱ = 3.1 T m) and a switching magnet with seven left- and seven right- side exit ports has also been completed. The instrumentation connected with the beam lines will already be equipped with a pulsing system (1 ns) and with different experimental devices for heavy ion detection, γ, and neutron spectroscopy, and mass spectrometry facilities.

The production of negative polarized heavy ions and their acceleration by tandem accelerators is reviewed. Particular emphasis is given to the polarized lithium and sodium beams at the Heidelberg EN tandem. The problem of depolarization of an incompletely-stripped beam is discussed using experimental results on the $\text{Na}$ beam as an example. The advantages involved in using tandems with high terminal voltages for the acceleration of polarized ion beams heavier than lithium is stressed.