6. Calibration with Photons

In order to experimentally test the performance of the pure CsI-crystals, an array of 26 crystals was assembled as displayed in Fig. 5.11 of the previous section. The main goals of the beam time in 1994 were:

1. Set up the electronics for a simultaneous operation of 26 CsI-crystal array and the active target with 76 channels.

2. Study the response of the CsI-array to a beam of 70 MeV positrons.

3. Make the trigger and perform a measurement of the decay p ->e⁺ n _e.

4. Measure the response of the CsI-array to 70 MeV photons.

The data analysis for items 2 and 3 above is described in [Ass 95]. The description of the method for measuring the lineshape of 70 MeV photons and the corresponding data-analysis is the subject of this chapter.

6.1 Method of the Calibration
6.2 Experimental Apparatus
6.3 Analysis of the Data
6.4 Results and Discussion