Lund, 18.06.2007. V.Avdeichikov

1. CsI(Tl) Demonstrator (3x3 module) In-Beam and Bench Tests. Problems and Solutions (Lund- Dubna CWG, presented by V.Avdeichikov) Module of 9 (3x3) CsI(Tl) elements, 20x20x100 mm**3 DSSD Photo Diodes DSSD – Si, 300 mkm, 1.85 mm pitch, 59.5x59.5 mm**2.CsI(Tl)/PD, 20x20(front)23x23(back)x100mm**3. Produced by St.Gobain, Khar’kov and China CompaniesPD – 10.5x11.5x0.300 mm**3. Light guide /CsI(Tl)/ to fit PD active area Lund, 18.06.2007. V.Avdeichikov

2. CsI(Tl) scintillators, the PD’s, APD’s and Double Sided Strip Detector

3. CsI(Tl) Demonstrator (3x3 module) • In-Beam and Bench Tests. Problems and Solutions • (Lund- Dubna CWG, presented by V.Avdeichikov) • Structure of the Si + CsI(Tl) element • a) Requirements on CsI(Tl) • - geometry – 20x20 (front), 23x23 (back), L=100 (200) mm; with or w/o tail • - Tl concentration ( c = 0.07 mol%), dc <0.7% • - surface treatment / mirror/ • - light collection uniformity – as best as possible ( for each crystal) • 2. Suppliers and Prices • - Shanghai SICCAS High Technology Corporation (20x20/23x23x100 mm**3) • - AMCRYS Ltd, Khar’kov (20x20/23/23x100, 20x20/23x23x200) • - St Gobain CRYSTALS ( 20x20/23x23 x100) • Bench tests / gammas, alphas/ • - wrapping material – Al foil, Tyvek paper, VM2000 ( Vikuit ESR) • - light collection • - efficiency of light collection 10x10x10 - 20x20x100 mm**2 • - tests with the PD and APD light readout • In-beam tests, protons, 180 MeV • - energy resolution • - light-energy relations, slope parameter (calibration) • - inelastic interaction, multiple scattering • - GEANT simulation • 5. Some useful info on Scintillators Lund, 18.06.2007. V.Avdeichikov

4. Companies and Prices Shanghai SICCAS High Technology Corporation: 100 mm, 20*20/23*23 mm2 (no lightguide) no wrapping US$ 200 € 148 ………………… ” ……………, ESR wrapping (special price?) US$ 200 € 148 AMCRYS Ltd, Kharkov 110 mm, 20*20/23*23 mm2 (lightguide 11*11 mm2), no wrapping US$ 172 € 127 210 mm, 20*20/26*26 mm2 (lightguide 11*11 mm ), no wrapping US $ 330 € 244 St Gobain CRYSTALS 110 mm, 20*20/23*23 mm2 (lightguide 11*11 mm2), teflon wrapping, optimized light € 1051 ………………………………. ” …………………………………non-optimized € 752 210 mm, 20*20/26*26 mm2 (lightguide 11*11 mm2), wrapping, optimized € 1551 ………………………………. ” …………………………………non-optimized € 916 (at least 25% reduction for big numbers is given) Lund, 18.06.2007. V.Avdeichikov

5. 3. Bench tests. Light collection and Light output uniformity Tested rapping materials 1. Al foil… 2. PFTE tape. 2. TYVEK paper/ used by ALICE/PHOS for PWO wrapping… 3. Vikuiti ESR ( Visual Mirror-2000 ) – the best, max. uniformity and max. Light Output…Almost 100% reflection!!!! Co60, Cs137 gammas wrapping Ris Fair 011.ps Light Output must be a) as high as possible, b) as uniform as possible along the crystal. DL defines an energyresolution / for gammas and particles / and energy scale linearity!!! Lund, 18.06.2007. V.Avdeichikov

6. Bench tests Light collection uniformity As supplied After correction Light output uniformity for supplied crystals and gamma spectroscopy measured by the CsI(Tl)/APD /left / and after our improvement in light uniformity / right Fig./. Lund, 18.06.2007. V.Avdeichikov

7. Correction of Light output uniformity “Focusing phenomenon” – a typical nonuniformity picture for long crystals. Primary ( as measured by Suppliers ) spread of Light Output along the crystal as measured by Cs137 gamma source) - open circles, and after our improvement - filled circles. The method consists in “shadowing” of back facet of crystal near the front face. The loss in Light Output due to thecorrection of the uniformity – 10 – 15%. Final L.O. spread dL<0.7% Lund, 18.06.2007. V.Avdeichikov

8. Loss of light, 10x10x10 mm**3 vs 20x20x100 mm**3 crystal Am, 59 keV Picture2 PD is used to calibrate the scale and to define noise level. R% down to 2.8keV is possible ( CMS/PHOS-CERN Preamp.). 10x10x10 mm**2 – an ideal crystal. R%(59.5 keV)=R% (Gen) = R (in keV) for g - lines!! Shaping = 3.0 mksec. Light collect. efficiency for 20x20x100 = 60-75% (of 10x10x10), for both shapes , see Fig. Crystals of excellent light uniformity, <0.7%. Lund, 18.06.2007. V.Avdeichikov

9. Bench test CsI(Tl)/APD, CsI(Tl)/PD !0x10x10 mm**3 ------------------------------------------------------------------------------------------------------- 20x20x100 mm**3 Test of crystals of different size with APD (left) and PD ( right) readout. No big difference for gamma energies >0.66 MeV. Lund, 18.06.2007. V.Avdeichikov

10. In-beam tests Uppsala, GWC, protons, 180.0 MeV 2 DE ( Si) - E (CsI(Tl)) method (Cu absorber is used to get second energy point, 93.3 MeV) CsI(Tl) - 9 elements, 20x20(23x23)x100 mm**3 Si – 7x7 mm*2, 310 mk 20x20 mm**2, 529 mkm DSSD – 16x16 strips, 310 mkm Data are taken for central detector Fig 7x7/CsI We measured : energy resolution, slope parameter a2, L=a1*exp(a2) +c, inelastic interaction, multiple scattering. Lund, 18.06.2007. V.Avdeichikov

11. Uppsala, GWC, protons, 180.0 MeV Energy resolution Energy resolution of CsI(Tl) detectors for protons, 180.0 MeV. Tl doping for Khar’kov - 0.07mol% - to get optimal particle identification in pulse shape analysis To get an energy resolution on the level <0.4% we need to stabilize the temperature of CsI(Tl) sample on the level better than 1 C Temperature dependence of Light output for CsI(Tl)/PD + electronic elements is 0.4%/1 C (GLAST Calorimeter data[]) Compilation of our data on the energy resolution Lund, 18.06.2007. V.Avdeichikov

12. In-beamtests Light-Energy relations. L=a1*exp(a2*E) + c a2 – slope parameter. Precision in a2 results in final energy resolution of CsI(Tl) as for charged particles, so for gammas !!!! a2 depends on shaping const, light collection uniformity and ??????? Data from this experiment Lund, 18.06.2007. V.Avdeichikov

13. In-beam test. Inelastic interactions (and multiple scattering) 20x20x100, CsI Si, 7x7 mm**2 or 60x60 mm**2 DSSD Comparison of the calculations and (our) experimental data of the particle losses due to the inelastic interactions in the CsI crystal. Thick dotted curves are calculations from Glauber model, thin dotted curves – from the complete fusion model. Point marked as big circle is taken from this in-beam test. To extract info about the multiple scattering we need to proceed with data analysis with Double Side Strip Detector Lund, 18.06.2007. V.Avdeichikov

14. GEANT simulation !!!! Simulation for the geometry of 40x40x100 mm**3 of CsI crystal Excellent coincidence with data !! except of…….shape of the “tail”… CsI(Tl) 40x40x100 mm**3 Inelastic interaction + multiple scattering Inelastic interactions Multiple scattering 190. MeV Lund, 18.06.2007. V.Avdeichikov

15. GEANT simulations B A The position and fraction of “washed out” events for geometry of 40x40x100 mm**3 CsI crystal. E_p=190 MeV D C Gain corrected sum signal in the central crystal of 3x3 PWO detector array ( ALICE) Attention to Fig. D !!! Almost 80% detection loss in the region about 3 mm from detector periphery (mostly because of multiple scattering) Lund, 18.06.2007. V.Avdeichikov

16. K_ampl.=50. Some useful info on scintillators Measurement of low-energy (say, less than 660 keV) gammas with quite reasonable resolution by using PD is a almost irresolvable problem… Signal from the PD is only 60 keV for 1.17 MeV gammas!!!!!! Energy resolution of the “ideal” CsI scint for gammas defined in great extent by the noise of PD+ Preamp.+ Shaper. Lund, 18.06.2007. V.Avdeichikov

17. Some useful info on scintillators Fig.5. Energy resolution of six different scintillators for alpha-particlesfrom the {226}Ra and {241}Am sources. Solid lines represent power law fits, R(%)=b1*exp(-b2*E) The alpha/gamma ratio - the ratio of the lightoutput of alpha-particle and gamma-rays with equalenergies. Data are taken with a 1.5 msec shaping time constantof main amplifier. Solid lines are drawn to guide an eye. Lund, 18.06.2007. V.Avdeichikov

18. CsI(Tl), 20x20(23x23)x100 mm**3 Module of 3x3 samles 3 2 1 6 5 4 9 8 7 We need: 1. GEANT simulation for given geometry 2. To analyze the multiple scattering 3. To prepare gamma tests??

19. Next steps ??