LPGD/Ditanet WS 11/2011 J. Pancin Low pressure gas detectors 6 th Ditanet Workshop on Particle Detection Technics Short review on low pressure gas detection Examples of detectors Current R&D on Secondary Electrons Detectors

LPGD/Ditanet WS 11/2011 J. Pancin History Low-pressure drift chambers for heavily ionizing particlesLow-pressure drift chambers for heavily ionizing particles Original Research Article Nuclear Instruments and Methods, Volume 119, July-August 1974, Pages 7-8 A. Breskin, G. Charpak, F. Sauli (methylal 300 mbar) 2 A low pressure multiwire proportional chamber as a position sensitive detector of heavy ions: Construction and detection properties Original Research Article Nuclear Instruments and Methods, Volume 177, Issues 2-3, 15 November 1980, Pages J. Stähler, G. Presser (iC 4 H mbar) A low pressure multiwire proportional chamber as a position sensitive detector of heavy ions: Construction and detection properties 3 Low-pressure drift chamber with a built-in scintillator Original Research Article Nuclear Instruments and Methods, Volume 178, Issue 1, 1 December 1980, Pages R. Janik, L. Mouc ̄ ka, V.D. Peshekhonov, B. Sitar (iC 4 H torr) Low-pressure drift chamber with a built-in scintillator 4 Application of a low pressure proportional chamber in ion X-ray coincidence measurements Original Research Article Nuclear Instruments and Methods, Volume 176, Issues 1-2, 1 October 1980, Pages J. Stähler, G. Presser (iC 4 H mbar)Application of a low pressure proportional chamber in ion X-ray coincidence measurements 5 A low pressure proportional chamber with a high space resolution Original Research Article Nuclear Instruments and Methods, Volume 145, Issue 3, 15 September 1977, Pages V.M. Golovatyuk, A.B. Ivanov, V.A. Nikitin, V.D. Peshekhonov, Yu.V. Zanevsky (methylal 300 mbar) A low pressure proportional chamber with a high space resolution 6 Low pressure multiwire proportional chambers with high time resolution for strongly ionizing particles Original Research Article Nuclear Instruments and Methods, Volume 94, Issue 1, 15 June 1971, Pages F. Binon, V.V. Bobyr, P. Duteil, M. Gouanere, L. Hugon, M. Spighel, J.P. Stroot (iC 4 H mbar)Low pressure multiwire proportional chambers with high time resolution for strongly ionizing particles 7 Properties of low-pressure drift chambers Original Research Article Nuclear Instruments and Methods, Volume 134, Issue 1, 1 April 1976, Pages A. Breskin, N. Trautner (methylal 10 torr)Properties of low-pressure drift chambers 8 Properties of different counting gases for a low pressure multiwire proportional chamber Original Research Article Nuclear Instruments and Methods, Volume 164, Issue 2, 15 August 1979, Pages J. Stähler, G. Hemmer, G. Presser (iC 4 H mbar)Properties of different counting gases for a low pressure multiwire proportional chamber

LPGD/Ditanet WS 11/2011 J. Pancin Detector types Progress in low-pressure gaseous detectors, A. Breskin et al., NIM196(1982): heavy and light ion detection Low Pressure detectors:  Few materials in beam (few angular or energy straggling for heavy low nuclei) and operation in vaccum  low pressure gas detector  Use of pure iC 4 H 10 for its low ionisation energy (about 100 % efficiency needed) and its high quenching power (very low pressure of several mbar)  Mean free path of electrons much higher : high electron drift speed, early avalanche and good timing resolution  Important gain (E/P…) even in low field region : natural spread of the avalanche, good spatial resolution with low granularity, low threshold applications  Low drift gap and fast ion collection for high rate capabilities

LPGD/Ditanet WS 11/2011 J. Pancin Signal at low pressure (…vs NTP) No much differences in the ionization process (apart for delta electrons…) Amplification process much easier at low pressure: +V 0 Signal Cathode Anode wire Isobutane Charged particle + - Ex Ei - Minimum field E c for avalanche multiplication ≈ 40 V/cm/torr d= 3 mm  V c ≈10 kV at 1bar - Increase E: wire chamber (α 1/r) - Decrease gaps: MPGD (micromegas, GEMs, MSGC) - Decrease Pressure !!

LPGD/Ditanet WS 11/2011 J. Pancin Signal at low pressure (…vs NTP) UV Gas mixture at NTP but pure at low pressure Polyatomic gases (several vibration and rotation modes: non radiative mode)  Absorbe the radiated photons  Limit the breakdown (at low pressure!!!)  Typical quenchers: i-C 4 H 10, CF 4...CO 2, CH 4 Avalanche appears earlier at low pressure

LPGD/Ditanet WS 11/2011 J. Pancin Electronical cross sections - Non radiative modes - Ionization energies - Ionization cross sections

LPGD/Ditanet WS 11/2011 J. Pancin Gain and Townsend coef. : Calculation at low pressure Yu. I. Davydov, IEEE TRANSACTIONS ON NUCLEAR SCIENCE, 53-5, (2006) Rose and korff approx: A=27 cm -1 Torr -1 and B=392 V cm -1 Torr -1 (183 to 438 V cm -1 Torr -1 ) If e< i α=1/ If e> i  Magboltz simulation for electron drift speed and diffusion (not the gain…)  Difficult to get some good simulations at low pressure :  ≈50  m at 10 mbar  α=f(dE) and electron not in equilibrum with electric field at VLP (PPAC vs WC)  Laboratory test mandatory to get the real performances M. Nakhostin et al, Nucl. Instr. And Meth., 572, (2007) assuming constant mean free path =1/(n  ) Ei= V/cm/Torr

LPGD/Ditanet WS 11/2011 J. Pancin Spatial resolution… 80 mbar iC 4 H 10 8 mbar iC 4 H 10

LPGD/Ditanet WS 11/2011 J. Pancin High ion drift speed 1.6 / =12.5… Mobility of iC 4 H 10 ion in itself: w=0.61 cm 2 V -1 s -1 v= wEP0/P  v ≈ 200*wE at 5 mbar which gives v ≈ 0.2 cm/  s at 2 kV/cm 1.6 / =6.25…  high couting rate capabilities v≈0.21 cm/  s

LPGD/Ditanet WS 11/2011 J. Pancin Detectors used at low pressure (in nuclear physics…) Tracking (X,Y,t) with Wire Chambers Energy loss (  E) measurements with ionization chambers: no amplification process Tracking (X,Y) with Drift Chambers (with very good spatial resolution) …

LPGD/Ditanet WS 11/2011 J. Pancin CATS: Beam Tracking Detectors (E>10 A.MeV) Constant field zone: PPAC, position signal on the strips High gradient field zone: MWPC, time signal on the wires  t <400 ps,  s <0.5 mm,  <1mrad Counting rate 10 5 pps/cm 2 Energy threshold ≈ 1 keV Material in beam 550  g/cm 2 11 C Proton E p ΘpΘp E* x 1,y 1 x2,y2x2,y2 xcxc S. Ottini-Hustache, NIMA 431 (1999).

LPGD/Ditanet WS 11/2011 J. Pancin Detectors used on VAMOSII Spectrometer 7 m MW target Big size MW 2 drift chambers 3 Ionization Chambers 1 wall of 40 Si tt X1,Y1X2,Y2 EE E 1 m A, Z, Q and v to measure for each nuclei entering spectrometer - energy E=1/2 Av 2, with Si detectors - Energy loss ΔE≈AZ 2 /E for Z, with Si detectors and ICs - Magnetic rigidity Bρ= Av/Q with the spectrometer and the DCs -Velocity v by TOF with the MW Dedicated to energy below 5 A.MeV : use of low pressure to minimize material in beam for all detectors M. Rejmund et al., Performance of the improved larger acceptance spectrometer: VAMOS++, Nucl. Inst. And Meth. A, 646 (2011), p

LPGD/Ditanet WS 11/2011 J. Pancin Small Multi-Wire target Active area 60x60mm  g/cm 2 or 120  g/cm 2 Time resolution (300ps) X, Y resolution (0.5 mm) Inverse polarisation for ion gating Counting rate 10 5 pps/cm 2 Energy thereshold ≈30 keV 2x2.4mm

LPGD/Ditanet WS 11/2011 J. Pancin Big size MWPPAC: alternative to SED (1 m) - Used on PRISMA with  t =300 ps (S. Beghini et al.,NIMA 551(2005)364) - Active area 1000x150 mm 2, 200  g/cm time signals shared by 2000 wires of 20  m diameter - Same characteristics than the small one… - Detector mechanics and Electronics still to define for spatial reconstruction

LPGD/Ditanet WS 11/2011 J. Pancin SED for beam tracking Beam tracking mandatory to reconstruct reaction kinematics (resolution of 1.5 mm and 250 ns, high counting rates) Dedicated to heavy nuclei or FF at low energy (<6-7 MeV/n) : SPIRAL2, FAIR, S 3 or NFS… Use of a Secondary Electrons Detector with an emissive foil (180 μg/cm2 max (45°) Different topics of work:  Detectors at very low pressure  Emissive foil or how to reduce thicknesses: study to perform end of 2011 (<60 μg/cm2 (45°))  Guiding of Secondary Electrons, B field mandatory  Electronics Construction of 4 low pressure gas prototypes 7×7 cm 2 since 2007: 2 wire chambers 1D and 2D and 2 micromegas Test benches to mesure spatial and time resolution at CEA Saclay and GANIL New electronics based on AFTER design, fitting with GANIL acquisition, for end 2011: AFTER-SED (necessary to qualify the detectors in spatial resolution) Test in beam realized in july 2010 on Real size proto. wire chamber in 2D mid-2011, full characterization for beginning of 2012, prototype shared between NFS and S3 R&D around micromegas at low pressure still on-going, a real size proto in 2012 depending on the last results Test in beam depending on the last results A. Drouart et al., NIMA579(2007) J. Pancin et al., JINST4:P12012(2009)

LPGD/Ditanet WS 11/2011 J. Pancin Test beam at GANIL in july Kr from CIME at 1.7 MeV/n from 10 3 to 10 5 pps/cm 2 - Emissive foil : mylar+Al 180  g/cm 2 - No magnetic field - 3 detectors in coincidence: an MCP first, then a SED and a collimated plastic at the end - Accurate measurements of time resolution - Influence of the counting rate on performances - Tests of a new electronics based on AFTER ASIC - 3 prototypes to tests: MiniSED, MiniSED2D, MumSED - In Collaboration with CEA (Saclay) and CNA (Sevilla) M. Alvarez et al, GANIL/STP226 PLASTIC collimated SeD prototyp e Se-Se- Emissive foil Se-Se- MCP 82 Kr

LPGD/Ditanet WS 11/2011 J. Pancin Prototypes tested in beam 3 prototypes partially tested in lab: − 1 mini-SED “classical” −1 mini-SED 2D −1 SED with micromegas: time to improve and still spatial to test

LPGD/Ditanet WS 11/2011 J. Pancin Spatial and time resolutions  Profile of the Plastic coll. FF signal with a SED with the AFTER ASIC  =1.4 mm (No B field)

LPGD/Ditanet WS 11/2011 J. Pancin Last micromegas results in lab. 3 micromegas prototypes tested so far: 128, 256 and 512  m amplification gap Good S/N ratio (efficiency with alphas around 40 %), much better than simple PPAC or WC Poor energy resolution Clear influence from ampl. gaps No so sensitive to ampl. Voltage for low gaps: α saturation at VLP Sparking limit due to bulk process and LP: no real gain at high counting rate… Good time resolution (2 mm gap) PPAC behavior Spatial resolution to measure SEDMW - Not really used at low pressure - Counting rate: same advantages than at NP ?? - S/N ratio - Time and spatial resolutions

LPGD/Ditanet WS 11/2011 J. Pancin Real size prototype - Common proto. between NFS and S3, - SED2D sym. chamber of 201×138 mm 2 or 68×47 1D strips - Mounted since sept 2011, tests on time resolution on-going - AFTER-SED ASIC to connect - Spatial resolution to be measured - Mumegas proto. same size beginning of next year (depending on results of SED2D)

LPGD/Ditanet WS 11/2011 J. Pancin Conclusion… Low pressure still widely used at least in nuclear physics Laboratory tests mandatory (like with other detection system but time consuming) Secondary Electrons Detectors to produce in the framework of SPIRAL2 or FAIR S3 and NFS real size prototype to be tested before mid-2012 (micromegas included)

LPGD/Ditanet WS 11/2011 J. Pancin People involved at CNA, GANIL and CEA/IRFU Electronics :T. Chaminade, F. Druillole, E. Monmarthe (IRFU) Detector tests : M. Kebbiri (IRFU), S. Damoy (GANIL) Mechanics :M. Riallot (IRFU), G. Fremont (GANIL) Scientific coordinator : M. Alvarez (CNA), H. Savajols, E. Clement, F. Farget (GANIL), A. Drouart, D. Doré, T. Materna (IRFU) Technical coordinator and analysis : B. Fernandez (CNA), J. Pancin (GANIL), T. Papaevangleou (IRFU) And the others…

LPGD/Ditanet WS 11/2011 J. Pancin GET Filter 511 cells Disc Pulser ADC Slow Control Power Clock X 76 Memory Bank Select External PA + Filter Adjustable Sample Size & Frequency ADC parameters Internal Trigger Calculated Read-Out Pattern Pattern/Trigger PA PA + Filter 1) 64 +/- input 2) 16 shaping times 3) Adjustable gain/ch