Tandem Accelerator Superconducting Cyclotron Research Articles

Channel selection for high spin γ-ray spectroscopy studies via total energy measurements in fusion-evaporation reactions

A channel selection method for high spin γ-ray spectroscopy studies based on the measurement of the total energy of all radiations (both charged particle and γ-ray) emitted in heavy-ion fusion reactions is presented. The method is applicable to all reactions in which charged-particle evaporation from the compound system dominates, and is particularly effective in isolating the weakly populated low particle multiplicity channels that leave the final nucleus with the greatest spin and excitation energy. The method is illustrated using data taken with the 8π γ-ray spectrometer and the miniball 4π charged-particle detector array at the Chalk River Tandem Accelerator Superconducting Cyclotron (TASCC) facility. Channel-to-total ratios are improved over those obtained with charged-particle detection alone by factors as large as 46 without significant loss of statistics for the selected channel.

A microwave-driven negative ion source

A 2.45 GHz microwave-driven ion source, originally developed to generate a high-current 1H+ beam, has been adapted to serve as a universal negative-ion injector for the Tandem Accelerator Superconducting Cyclotron (TASCC) facility. Positive heavy ion currents from the source are converted into negative currents by means of a charge-exchange canal. So far, beams of 4He−, 16O−, and 18O− have been accelerated through the TASCC Tandem and 3He− and 209Bi− beams were accelerated through both the TASCC Tandem and cyclotron. A production version of the source has been designed, with emphasis on enhanced compactness and serviceability.

Development of the Chalk River program for 36Cl

The AMS program at the Chalk River TASCC (Tandem Accelerator Superconducting Cyclotron) facility is directed toward 36Cl measurements in hydrological and other samples. The automatic data acquisition/accelerator control system has been commissioned and progress is reported on particle identification with a Bragg-type detector and 36S background control with a gas-filled beamline magnet. Evidence for large Cl memory effects in a Hiconex 860 sputter source is also presented.

A CAMAC-resident microprocessor used for field control of a dipole magnet

An inexpensive, self-contained microprocessor supporting an on-chip BASIC interpreter has been incorporated into a CAMAC auxiliary-crate controller, with an EEPROM and a terminal port. Used with an ASCII computer terminal, the intelligent auxiliary controller is a self-contained program-development system. One application for the intelligent auxiliary controller is closed-loop control of the analyzing dipoles at the negative-ion injector of the TASCC (tandem accelerator superconducting cyclotron) heavy-ion accelerators. A BASIC program stored in the EEPROM runs on power-up of the controller. The program reads control numbers from a CAMAC mailbox, converts the ASCII character string from a precision Hall-probe teslameter to a digital field reading, and writes a control number to the dipole controller. The program iterates until the dipole reaches the demand field, while updating another CAMAC mailbox with a field readback for the main control system.

Charge-state measurements for 63Cu, 90Zr, 107Ag, 115In, 127I and 197Au in carbon for energies below 1 MeV/u

Equilibrium charge-state distributions have been measured for ∼0.2–1.0 MeV/u 63Cu, 90Zr, 107Ag, 115In, 127I and 197 emerging from thin (10–30 μg/cm2) carbon foils. In many cases, values deduced for the mean charge were found to deviate substantially (from 1 to 3 charge states) from those predicted by semi-empirical formulae. Highly asymmetric charge-state distributions were observed for 107Ag and 115In near 30 MeV, which are attributed to a shell effect at the boundary between the N- and M-shell electrons. The present results will be used to select the optimum charge-state combinations for heavy-ion beams from the tandem accelerator superconducting cyclotron (TASCC) at Chalk River.

Canadian fusion breeder blanket program: Irradiation facilities at chalk river

The major irradiation facility at Chalk River Nuclear Laboratories (CRNL) is the NRU research reactor. Both unvented and vented capsule experiments on candidate blanket ceramics can be performed. In the unvented tests, tritium release data (HT-to-HTO ratio, tritium retention) are obtained by post-irradiation heating of the breeder ceramic in the presence of a sweep gas. Four tests have been completed on Li 2O and LiAlO 2. Effects of sweep gas composition, extraction vessel material and ceramic properties have been determined. Two unvented irradiations under the BEATRIX international breeder exchange program have been completed; analysis is underway. The vented tests involve long-term irradiation of candidate blanket materials. CRITIC-I, scheduled for mid-1986 under BEATRIX, will examine ANL-fabricated Li 2O in a six-month irradiation at 700–1200 K, varying sweep gas composition, with on-line HT/HTO measurement. Additionally, accelerator simulation techniques are available, using 70 kV and 2.0 MV mass separators, a 2.5 MV Van de Graaff accelerator and a tandem accelerator super-conducting cyclotron, the latter allowing irradiation with protons, deuterons or helium at 18–20 MeV.

First accelerated beam in the Chalk River tandem accelerator superconducting cyclotron (TASCC) facility

The Chalk River TASCC facility consists of a 13-MV tandem accelerator injecting into a four sector k=520 (ME/q2) superconducting cyclotron that is designed to accelerate all ions from lithium (up to 50 MeV/u) to uranium (up to 10 MeV/u). This report describes the first stages of commissioning in which an iodine-127 beam was accelerated by the tandem to an energy of 71 MeV, injected into the cyclotron and accelerated to a final energy of 1.2 GeV.

The safety interlock system for the Chalk River tandem accelerator superconducting cyclotron (TASCC) facility

The Chalk River TASCC Facility consists of a 13 MV tandem accelerator injecting into a K = 520( ME q 2 ) superconducting cyclotron. A microcomputer-based safety interlock system is used to monitor a variety of hazards and automatically initiate protective actions based on the monitored information. Inputs to and outputs from the system are handled by remote stations that communicate with the control room via a serial highway. Information on all monitored hazards is displayed in the control room on a colour video terminal; the path of the beam and radiation levels are displayed on a large plan view of the TASCC Facility. Several smaller displays are located around the Facility.

First Operation of the TASCC Beam Bunching System

The Chalk River Tandem Accelerator Superconducting Cyclotron (TASCC) system uses a low-energy buncher (LER) and a high-energy rebuncher (HER) to prodtice the required bunched beam at the cyclotron injection stripper foil. The LEB modulates the < 300 keV beam from the negative ion source with a f?undamental plus 2nd harmonic approximation to an ideal saw tooth to give a time focus at the stripper in the tandem accelerator terminal. The HEB, operating at the 2nd or 4th harmonic, corrects for debunching after the stripper and produces a new time focus at the cyclotron stripper. Transit time jitter through the tandem accelerator is corrected by a phase stabilizing circuit using both energy analysis after the HEB and a correlation with a capacitive phase probe signal . In the first experiments with a low energy 12C beam, the LEB produced bunch lengths of about 1.6 ns and the HEB produced the expected energy dispersion. Beam tests will be described.

Semi-Automatic Prodedures for Matching the Emittance of the Injected Beam to the Chilk River Superconducting Cyclotron

A system of programs and procedures has been developed that allows efficient matching of the MP Tandem beam to the superconducting cyclotron. The Chalk River Tandem AcceleratorSuperconducting Cyclotron project (TASCC) consists of a 13 MV tandem injecting into a K=520 (MeV A/Q/sup 2/) superconducting cyclotron. In order to minimize the radial and axial betatron amplitudes in the cyclotron, and to maximize the quality of the extracted beam, precise 6-dimensional emittance matching to the cyclotron is required. This paper deals with semi-automatic procedures for matching the emittance of the beam to the continuously variable optical properties of the cyclotron in order to meet its rather stringent yet variable acceptance phase space.

The Beam Bunching System for the Chalk River Superconducting Cyclotron

The bunching system for the tandem accelerator-superconducting cyclotron is of the buncher-rebuncher type. It consists of a low energy gridded buncher before the tandem that produces a time focus at the tandem stripper, combined with a high energy buncher between the tandem and the cyclotron to correct for debunching of the beam produced by energy straggling in the stripper. To meet the cyclotron design energy resolution of 5:10<4 the bunch length produced at the cyclotron has to be less than three degrees in rf phase.