Development of a neutron spectrometer, counter telescope with thick radiator, for TFTR D‐T experiments

A ΔE‐E type proton recoil telescope, called COTETRA, was developed and is presently being applied to TFTR D‐T fusion experiments. Two types of COTETRA were prepared for this experiment. One set is used primarily for high‐resolution measurements of the neutron energy and uses Si diode as an E detector (set A), while another set (set B) uses a plastic scintillator to attain high count‐rate capability. Both sets of COTETRA have small physical dimensions and use fast NIM electronic modules for high neutron flux rate measurements. A data acquisition system has been developed for the TFTR CAMAC system. A calibration experiment has been performed using a D‐T neutron generator. Energy resolution of 4.0% is obtained for set A. Set B is expected to work at a count rate of up to 104 cps, which corresponds to a neutron flux rate of ∼109 (n/cm2)/s at the detector position. Currently, both of them are installed under the multichannel neutron collimator of TFTR.