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PNPI R&D on based detector for MUCH central part (supported by INTAS 06-1000012-8781)

PNPI R&D on based detector for MUCH central part (supported by INTAS 06-1000012-8781) E. Chernyshova, V.Evseev, V. Ivanov, A. Khanzadeev, B. Komkov, L. Kudin, V.Nikulin, G. Rybakov, E. Rostchin, V.Samsonov, O.Tarasenkova, S. Volkov. A.Khanzdeev, March_2009, GSI.

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PNPI R&D on based detector for MUCH central part (supported by INTAS 06-1000012-8781)

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  1. PNPI R&D on based detector for MUCH central part (supported by INTAS 06-1000012-8781) E. Chernyshova, V.Evseev, V. Ivanov, A. Khanzadeev, B. Komkov, L. Kudin, V.Nikulin, G. Rybakov, E. Rostchin, V.Samsonov, O.Tarasenkova, S. Volkov A.Khanzdeev, March_2009, GSI

  2. Main steps of R&D at present stage: ■ Choosing the working gas ■ Radiation hardness of materials ■ Designing the beam test prototypes A.Khanzdeev, March_2009, GSI

  3. GEM+MICROMEGAS MICROMEGAS+GEM based tracking detector is considered as candidate for central region. GEM (5x5 cm2) of CERN production For MICROMEGAS it was used rolled mesh of Russian production – stainless steel (wire - 32 μm in diameter, cell - 64μm). Pillars made by chemical etching from photo-resistant layer 4mm between pillars, diameter of each pillar - 300μm, height - 75μm A.Khanzdeev, March_2009, GSI

  4. At previous R&D stage we worked with He/CO2 and Ar/CO2 mixtures. New gas supply system for preparation of 3-component gas mixtures(designed and produced in the end of last year) allowed to study Ar/CO2/iC4H10, He/CO2/iC4H10, Ar/CF4/iC4H10, and He/CF4/iC4H10. Gas gain vs. voltage in the mesh-gem region Gas gain vs. voltage in the gem-cathode region Voltage into the drift gaps was always kept - 1500 V/cm A.Khanzdeev, March_2009, GSI

  5. Small addition of isobutane gives huge effect. The same values of gas gain are reached at much lower HV. Almost twice less energy of dischargefor the same value of gas gain ~ 100 Volts A.Khanzdeev, March_2009, GSI

  6. The mixture He/CF4/iC4H10 (90/8/2) showed much lower spark probability in comparing to 2-component mixture. Gas gain of 2∙107 is reached at 450 V applied to the mesh and GEM (visible spark problems occurred at 480 V). Current design of FEE supposes gas gain value of 2∙104 which is reached at 300 V. Last point that we tried to measure was at 350 V (gas gain of ~ 2∙105) and during 30 hours we did not detect any sparks (in the picture the last point is result of extrapolation). For Ar/CF4/iC4H10 (90/8/2) mixture sparks were observed at 380 V β-source 90Sr (~3∙105 counts/s) Spark probability was estimated as ratio of spark number (count of the signals laying above some high threshold and detected by the mesh) to number of total counts detected by the anode A.Khanzdeev, March_2009, GSI

  7. Why He and CF4? Transversal diffusion for He/CF4/iC4H10 almost twice less than for Ar/CF4/iC4H10 or He/CO2/iC4H10 calculations σd=k√x (μm),where x in cm For 5 mm drift distance σd≈ 100μm in the best case A.Khanzdeev, Martch_2009, GSI

  8. Using He/CF4/iC4H10 (85/13/2) we can get collection time of ions in the mesh-anode gap plus drift time of electrons passing drift gaps at the level of 100-150 ns A.Khanzdeev, March_2009, GSI

  9. Drawback– number of produced pairs in He based gas mixture is ~4 times less than in Ar −inefficiency Looks reasonable to try He + Ar (20%, for example) Ar+ He+ Inefficiency ~0.5% ~3.8% ~2% ~1% He+20%Ar+ He+10%Ar+ A.Khanzdeev, March_2009, GSI

  10. Radiation hardness of construction materials Co60(E=1.25 MeV) → two expositions of 390 krad and 5.3 Mrad After irradiation the emitted fractions were detected and analyzed by infrared spectroscopy method polyethylene kapton FR4 Red – 5.3 Mrad,blue -390 krad Coefficient of radiation degradation afterdose of 5.3 Mrad Radiation degradation Prices of flan and kapton about 10 times higher than FR4 There is not cupper covered noril, noril is 2 times more expensive than FR4 kapton (polyimid) noril flan FR4 polyethylene A.Khanzdeev, March_2009, GSI

  11. Prototype for beam test A.Khanzdeev, March_2009, GSI

  12. Schematics A.Khanzdeev, March_2009, GSI

  13. Prototype chamber elements Front-end electronics boards Anod boards Mesh frames A.Khanzdeev, March_2009, GSI

  14. Anode structure: • 2048 pads; • Pad size 1.5x 3 mm2; • Working area 102x109 mm2; • Gap between pads 0.2 mm; • Mask-pad overlap 0.05-0.075 mm; • Through hole diameter 0.5 mm; • Board thickness 1mm A.Khanzdeev, March_2009, GSI

  15. Plans for this year ■ Try He+Ar based gas mixture ■ Measuring the collection time for chosen working gas ■ Building two prototypes (MICROMEGAS+GEM and MICROMEGAS+TGEM) for beam test ■ Preparing electronics for beam test ■ Would be nice to start beam test at PNPI accelerator A.Khanzdeev, March_2009, GSI

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