Electron telescope measurements

 

Table 6.8: The results of fit to the electron telescope time spectrum for the sum of Runs 1650 and 1654, to be compared with the scintillator fit in Table 6.6. The fits for Telescope 1 (Tel1), located on the beam left, and Telescope 2 (Tel2) downstream, together with first hit of the two (1st) are listed.

Det.	A1/Q1	A2	bkgd				$\chi ^{2}$/dof(cl)
	(10-2)	(10-3)	(10-8)	(ns)	($\mu$s)	(%)
Tel1	1.43(3)	8.19(2)	2.3(2)	79.1(16)	2.092(6)	36.34(38)	1.02 (18%)
Tel2	1.48(3)	7.21(2)	5.4(2)	78.5(16)	2.089(7)	32.81(36)	1.07 (.04%)
1st	2.90(4)	15.4(3)	7.6(3)	78.8(11)	2.089(4)	34.66(34)	1.06 (.3%)

 

The liquid NE213 scintillation detectors, normally used for fusion neutron detection, can be used as charged particle detectors by reading out a fast dynode signal. We define a telescope event as the event in which the dynode fires in coincidence with the pair of plastic scintillators in front of it. Telescope 1 (Tel1) is in the beam right position (as is Neutron 1 or N1), while Telescope 2 (Tel2) was in the downstream position; both used an independent data acquisition trigger.

Given in Table 6.8 are the results of fits to the telescope spectra and derived reduced stopping fractions . The fits were performed in the time region of [0.02; 9.5] $\mu$s, and the time spectra were obtained with a ``nominal'' energy cut on the dynode output, which was 200 ch< E_dy<1200 ch. Fits in this section are done to the sum of runs 1650 and 1654. As can be observed in a comparison of Tables 6.6 and 6.8, the stopping fractions given by the telescopes were systematically higher than those from the electron scintillators. We shall look into possible effects due to the difference in the energy sensitivity of the detectors in the following section.