Temperature dependence of the energy resolution of the new CCD-22.

Stage two of the DEAR setup will use in total 16 of the new CCD-22 chips to be cooled below 180 K in order to increase the performance, specially the energy resolution and the efficiency of the CCDs. Two refrigerators (APD Cryo Tiger) are foreseen for the cooling process.

For a precision experiment, as planned in the DEAR case, the performance of the new CCD-22 detector system is of great importance and, therefore,  the CCD-22 detector system was carefully investigated in the DEAR laboratory. One of the studies was the measurement of the dependence of the energy resolution on the CCD temperature.

The plot shows the FWHM energy resolution dependence on temperature, measured with a 55Fe source . As expected, an exponential behaviour of the energy resolution can be seen reaching the minimum value at about 180 K. These data proof clearly the importance of cooling the CCD chips to a temperature below 180 K, which is the planned value of the project.