1 / 22

RPC working gas (C 2 H 2 F 4 /i-C 4 H 10 /SF 6 ): Simulation and measurement

RPC working gas (C 2 H 2 F 4 /i-C 4 H 10 /SF 6 ): Simulation and measurement. Jingbo Wang Department of Engineering Physics, Tsinghua University, Beijing, China. 10th RD51 Collaboration Meeting , Oct 4th, 2012, Stony Brook. Outline. Multi-gap Resistive Plate Chamber (MRPC)

kaiya
Télécharger la présentation

RPC working gas (C 2 H 2 F 4 /i-C 4 H 10 /SF 6 ): Simulation and measurement

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. RPC working gas (C2H2F4/i-C4H10/SF6): Simulation and measurement Jingbo Wang Department of Engineering Physics, Tsinghua University, Beijing, China 10th RD51 Collaboration Meeting, Oct 4th, 2012, Stony Brook

  2. Outline • Multi-gap Resistive Plate Chamber (MRPC) • Motivation of the simulation • Experimental measurements • C2H2F4, J de Urquijo • i-C4H10, I.B. Lima, P. Fonte • SF6, L. G. Christophorou • Mixtures, G. Chiodini, A. Colucci • Simulations of the swarm parameters • Garfield++ • Magboltz 8.9.2 • Summary

  3. Multi-gap Resistive Plate Chamber (MRPC) differential pre-amplifier particle standard PCB with read-out strips on one side HV distribution by a medium resistivity layer (e.g. Graphite) transparent to the induced signals Rin HV insulator +HV gas gaps (~0.22 mm) -HV HV coating with R~2 MΩ/□ Resistive electrodes (glass. bakelite) Time resolution: 20 - 100 ps Efficiency: >90% * The multi-gap structure: E. Cerron Zeballos, et al., Nucl. Instr. and Meth. A 374 (1996) 132.

  4. MRPCs @ Tsinghua STAR-TOF STAR-MTD 4032 modules for STAR-TOF 120 modules for STAR-MTD CBM-TOF Y. Wang, J. Wang, et al., Nucl. Instr. and Meth A 613 (2010) 200–206 Y. Wang, et al., Nucl. Instr. and Meth A 640 (2011) 85–90 J. Wang, et al., Nucl. Instr. and Meth. A 621 (2010) 151. Rate capability: >20 kHz/cm2

  5. MRPCs @ Tsinghua Low-resistivity doped glass 50cm * 50cm ~1010Ωcm MRPC Workshop modules for STAR-TOF modules for STAR-MTD Modules for CBM-TOF: rate capability up to 70kHz/cm2

  6. l E x Ions Electrons Motivation of the simulation • n(t) increases exponentially • α*Ve dominates the time resolution. • Timing RPC is working in avalanche mode, under space charge regime • RPC wroking gas: C2H2F4/i-C4H10/SF6 First step: the latest electron swarm parameters Region: A, B, C, D, E 1.5-D model (Lippmann): a factor of 2 discrepency in the charge spectrum • intrinsic time resolution: sT ~ 50 ps • rate capability: R ~ 0.5 – 25 kHz/cm2 W. Riegler, et al., Nucl. Instr. and Meth A 500 (2003) 144–162 C. Lippmann, et al., Nucl. Instr. and Meth. A 517 (2004) 54–76

  7. Experimental measurement: C2H2F4 The initial electrons were released by a UV flash. Pulse Townsend technique! Current fit The displacement current was fitted by the expression: Te J. de Urquijo, et al., Eur. Phys. J. D 51, 241–246 (2009) J. de Urquijo, et al., 1999 J. Phys. D: Appl. Phys. 32 41 J.L. Hern´andez-´Avila, E. Basurto, J. de Urquijo, J. Phys. D 35, 2264 (2002), and references therein J. de Urquijo

  8. Experimental measurement: i-C4H10 • I.B. Lima Chamber Current fit P. Fonte, et al., Nucl. Instr. and Meth. A 613 (2010) 40–45 I.B. Lima, et al., Nucl. Instr. and Meth. A 670 (2012) 55–60 P. Fonte

  9. Experimental measurements: Mixtures • G. Chiodini, • C2H2F4/i-C4H10/SF6 = 94.7/5/0.3 The alpha in figure is performed with the empirical formula α*/P VS p/E • A. Colucci, C2H2F4/i-C4H10 = 97/3, 90/10 A. Colucci, et al., Nucl. Instr. and Meth. A 425 (1999) 84-91 G. Chiodini, et al., Nucl. Instr. and Meth. A 602 (2009) 757-760

  10. Simulations of the electron swarm parameters [1] [2] [1] R. Veenhof, Garfield - simulation of gaseous detectors, http://garfieldpp.web.cern.ch/garfieldpp/ [2] S.F. Biagi, Nucl. Instr. and Meth. A 421 (1999) 234Ð240 • Garfield++ • C2H2F4 • Iso-butane • SF6 • Mixtures • Magboltz 8.9.2 • Different solutions in Magboltz • Comparison between simulations and measurements • Cross-sections

  11. Garfield++: C2H2F4, Ve C2H2F4 / Ar mixture 100/0 50/50 20/80 10/90 Nice agreement! Data: J de Urquijo, et, al., Eur. Phys. J. D 51, 241–246 (2009)

  12. Garfield++: C2H2F4, Alpha* C2H2F4 / Ar mixture 100/0 50/50 20/80 10/90 Nice agreement! Data: J de Urquijo, et, al., Eur. Phys. J. D 51, 241–246 (2009)

  13. Garfield++: C2H2F4, Dl C2H2F4 / Ar mixture 100/0 50/50 10/90 20/80 Data: J de Urquijo, et, al., Eur. Phys. J. D 51, 241–246 (2009)

  14. Garfield++: i-C4H10, Alpha and Ve VS Magboltz 2.8.6 (very old version) Garfield++ (latest version) [1] P. Fonte [2] I.B. Lima RPC working point: 400 Td [1] P. Fonte, et, al., Nucl. Instr. and Meth. A 613 (2010) 40–45 [2] I.B. Lima et, al., Nucl. Instr. and Meth. A670 (2012) 55–60 Nothing has changed with i-C4H10

  15. Garfield++: SF6,Alpha*, Ve Ve Alpha* L. G. Christophorou, et, al., J. Phys. Chem. Ref. Data, Vol 29, No. 3, 2000

  16. Garfield++: Mixtures, Alpha* and Ve Magboltz 7.0 Garfield++ / Magboltz 8.9.7 P. Fonte, not published Disagreement for RPC gas mixtures (C2H2F4, i-C4H10, SF6) D. Gonzalez-Diaz, et, al., Nucl. Instr. and Meth. A 661 (2012) S172–S176

  17. Different solutions in Magboltz 8.9.2 Experimental definitions A constant number of electrons is emitted at the cathode, which generates a steady stream of electrons in the uniform electric field between parallel plates. A group of electrons is released at the cathode and its growth observed by measuring the external current a function of time. The growth is observed as a function of both position and time. Garfield++ takes the SST solution for alpha (MC solution if no SST output), and the MC solution for the others. • SST: Steady-state Townsend Solution • Drift velocity: Ve • Transvers diffusion: Dt • Longitudinal diffusion: Dl • Townsend coefficient: Alpha • Attachment coefficient: Att • PT: Pulsed Townsend Solution • Ionization rate: Ri • Attachment rate: Ra • TOF: Time-of-flight Solution • Drift velocity: Wr, Ws • Transvers diffusion: Dt • Longitudinal diffusion: Dl • Effective Townsend coefficient: Alpha-Att • MC: Monte Carlo (theoretical) solution: Ve, Dt, Dl, Alpha, Att Y Sakai, et, al., J. Phys. D: Phy., Vol. 10, 1977

  18. Magboltz 8.9.2: Alpha* C2H2F4 / Ar mixture SST solution MC solution Alpha*/N Space charge correction? Question: which solution is recommended? Data: J de Urquijo, et, al., Eur. Phys. J. D 51, 241–246 (2009)

  19. Magboltz 8.9.2: Ve C2H2F4 / Ar mixture MC solution SST solution Ve

  20. Magboltz 8.9.2: Dl C2H2F4 / Ar mixture SST solution MC solution NDL

  21. Cross-sections C2H2F4 dissociation

  22. Summary Thanks for your attention • Garfield++ and Magboltz: • C2H2F4: Fine • i-C4H10: ? • SF6: Tiny discrepancy • Mixtures: ? • Different solutions in Magboltz • Measurements for RPC gas mixtures are needed.

More Related