Light Output Uniformity of Long Cs ITl crystals

Straggling and Nonlinearity for Protons and Gammas due to d. L/L Effect of crystal

Test with highly uniform in Light Output Crystal , L=110 mm, d. L/L <0.

Effect of VM 200 ( ESR) Light Guide reflector on Light collection and Energy

Some Conclusions and Plans for Future R&D 1. 2. 3. Light Output uniformity for

Slides: 5

Light Output Uniformity of Long Cs. I(Tl) crystals the “bottle-neck” for gamma and proton spectroscopy Light Output Uniformity for Cs. I(Tl) as supplied by manufacturers… …and Energy Resolution for gammas, measured by a APD ( 5 x 5), when irradiating the whole crystal volume… * source L=110 mm Cs. I(Tl), L=110 mm 20 x 20 Lund-Dubna, VC_2007_12_13

Straggling and Nonlinearity for Protons and Gammas due to d. L/L Effect of crystal Light Output nonuniformity ( a)- 5%, b)-10% on the Light collected by Photodetector. Calculated for Protons. For Gammas – the picture looks similar, but with energy scaled by factor 1/4 - 1/5. Conclusion – d. LO/LO must be less than 1% along the length of crystal Lund-Dubna, VC_2007_12_13

Test with highly uniform in Light Output Crystal , L=110 mm, d. L/L <0. 7% Cs. I(Tl) – 20 x 20 – 110 – 23 x 23 mm**3 Irradiated for 110 mm distance… Photodetectors: PD – 10 x 10 mm**2 APD – 5 x 5 mm**2 / <M>=40 APD – 10 x 10 mm**2 / <M>=50 Our data… compare APD of 5 x 5 and 10 x 10 mm**2 !!!! Published data, 10 x 10 mm**3 Cs. I(Tl)+ 10 x 10 APD Lund-Dubna, VC_2007_12_13 !!!

Effect of VM 200 ( ESR) Light Guide reflector on Light collection and Energy Resolution a) - Active area of APD = Active area of Light Guide, 10 x 10 mm**2. S_APD/S_LG =1. 0 b) - Active area of APD = 0. 25 of Active area of Light Guide, 5 x 5 mm**2. c) d) e) f) g) a) S_APD/S_LG =0. 25 Light Collection coefficient, L(5 x 5)/L(10 x 10) = 0. 65, due to the VM 2000 (ESR) reflector, covering an extra surface By using an APD of 10 x 10 mm**2 we can gain around 12% in the energy resolution as compared with the APD of 5 x 5 mm**2 Lund-Dubna, VC_2007_12_13 b)

Some Conclusions and Plans for Future R&D 1. 2. 3. Light Output uniformity for Long crystals is more important than the active area of the APD For the highly uniform in L. O. crystals we can get almost ideal Energy Resolution New groups must be involved in the Uniformity Problem for real Califa geometries Plans for nearest future: 1. Light Uniformity adjustment for the real CALIFA crystal geometry 2. Tests with APD’s, PMT’s / like R 7400 U-3, 20 – insensitive to magnetic field 3. To mount Cs. I(Tl) “demonstrator” for bench and in-beam tests Lund-Dubna, VC_2007_12_13