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 Companies PD – 10.5x11.5x0.300 mm**3. Light guide /CsI(Tl)/ to fit PD active area Lund, V.Avdeichikov DSSD Module of 9 (3x3) CsI(Tl) elements, 20x20x100 mm**3 Photo Diodes CsI(Tl) Demonstrator (3x3 module) In-Beam and Bench Tests. Problems and Solutions (Lund- Dubna CWG, presented by V.Avdeichikov)

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

CsI(Tl) Demonstrator (3x3 module) In-Beam and Bench Tests. Problems and Solutions (Lund- Dubna CWG, presented by V.Avdeichikov) 1.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%),  c <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) 3.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 4.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, V.Avdeichikov

Shanghai SICCAS High Technology Corporation: 100 mm, 20*20/23*23 mm 2 (no lightguide) no wrapping US$ 200 € 148 ………………… ” ……………, ESR wrapping (special price?)US$ 200 € 148 AMCRYS Ltd, Kharkov 110 mm, 20*20/23*23 mm 2 (lightguide 11*11 mm 2 ), no wrappingUS$ 172 € mm, 20*20/26*26 mm 2 (lightguide 11*11 mm ), no wrapping US $ 330 € 244 St Gobain CRYSTALS 110 mm, 20*20/23*23 mm 2 (lightguide 11*11 mm 2 ), teflon wrapping, optimized light € 1051 ………………………………. ” …………………………………non-optimized € mm, 20*20/26*26 mm 2 (lightguide 11*11 mm 2 ), wrapping, optimized € 1551 ………………………………. ” …………………………………non-optimized € 916 (at least 25% reduction for big numbers is given) Companies and Prices Lund, V.Avdeichikov

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 ) – the best, max. uniformity and max. Light Output…Almost 100% reflection!!!! wrapping Ris Fair 011.ps Light Output must be a) as high as possible, b) as uniform as possible along the crystal.  L defines an energy resolution / for gammas and particles / and energy scale linearity!!! Lund, V.Avdeichikov Co60, Cs137 gammas

Bench tests Light collection uniformity 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, V.Avdeichikov As suppliedAfter correction

“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 the correction of the uniformity – 10 – 15%. Final L.O. spread dL<0.7% Correction of Light output uniformity Lund, V.Avdeichikov

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  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, V.Avdeichikov Picture2 Loss of light, 10x10x10 mm**3 vs 20x20x100 mm**3 crystal Am, 59 keV

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, V.Avdeichikov

In-beam tests Fig 7x7/CsI  Si) -  (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 Uppsala, GWC, protons, MeV We measured : energy resolution, slope parameter a2, L=a1*exp(a2) +c, inelastic interaction, multiple scattering. Data are taken for central detector Lund, V.Avdeichikov 2

Uppsala, GWC, protons, MeV Energy resolution Energy resolution of CsI(Tl) detectors for protons, MeV. Tl doping for Khar’kov mol% - to get optimal particle identification in pulse shape analysis Compilation of our data on the energy resolution Temperature dependence of Light output for CsI(Tl)/PD + electronic elements is 0.4%/1 C (GLAST Calorimeter data[]) 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 Lund, V.Avdeichikov

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

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, V.Avdeichikov

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

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

Energy resolution of the “ideal” CsI scint for gammas defined in great extent by the noise of PD+ Preamp.+ Shaper. 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!!!!!! Lund, V.Avdeichikov Some useful info on scintillators K_ampl.=50.

Some useful info on scintillators Fig.5. Energy resolution of six different scintillators for alpha- particles from 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 light output of alpha-particle and gamma-rays with equal energies. Data are taken with a 1.5 msec shaping time constant of main amplifier. Solid lines are drawn to guide an eye. Lund, V.Avdeichikov

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