Direct charge digital readout of dual phase Time

Direct charge digital readout of dual phase Time Projection Chambers with Grid. Pix M. Alfonsi, N. van Bakel, A. P. Colijn, M. P. Decowski, H. van der Graaf, R. Schön, A. Tiseni, C. Tunnell MPGD 2013 Conference, Zaragoza July 1 -4, 2012

The Grid. Pix detector • • • MPGD 2013, Zaragoza July 2 nd, 2013 Micro-Pattern Gaseous Detector with pixel readout Aluminum mesh supported by pillars (50 µm gap) Wafer post-processing (MEMS) Timepix readout (256 x 256 pixels, 55 µm pitch) 4 -8 µm resistive layer (spark protection) M. Alfonsi 2

The Grid. Pix detector • • • Micro-Pattern Gaseous Detector with pixel readout Aluminum mesh supported by pillars (50 µm gap) Wafer post-processing (MEMS) Timepix readout (256 x 256 pixels, 55 µm pitch) 4 -8 µm resistive layer (spark protection) • Single electron detection efficiency > 98% • < 20 µm spatial resolution • Time coordinate (µTPC) • Low noise (no dark counts) MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 2

Dual phase noble gas TPC • Prompt light (S 1) is collected by photodetectors arrays, electrons drift to liquid surface • Charge is converted to light in the gas phase by proportional scintillation (S 2) • Time Projection Chamber: Z from S 2 – S 1 time delay • S 1/S 2 ratio: large discrimination power between electronic and nuclear recoils MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 3

Direct charge readout • Within the DARWIN Consortium [ar. Xiv: 1012. 4767], we investigate Grid. Pix as direct charge readout • High spatial resolution Ø digital readout approach (high energy resolution at few e-) • Low noise (no dark counts) • Small device, mainly silicon, manufacturing processes: Ø Radiopurity Ø Low outgassing MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 4

Digital readout approach MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 5

Electroluminescence gain • Energy deposits from nuclear recoils up to 40 ke. V (e. g. Dark Matter searches) ~ few to 200 ionization electrons (depending on setup) make the S 2 MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 6

Electroluminescence gain • Energy deposits from nuclear recoils up to 40 ke. V (e. g. Dark Matter searches) ~ few to 200 ionization electrons (depending on setup) make the S 2 • Fluctuations to S 2 due to: 1. Electroluminescence gain (proportional) 2. Light Collection Efficiency & PMT quantum efficiency (5 -20% typical) Xenon Gain 31. 4 sigma 7. 5 MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 6

Electroluminescence gain • Energy deposits from nuclear recoils up to 40 ke. V (e. g. Dark Matter searches) ~ few to 200 ionization electrons (depending on setup) make the S 2 • Fluctuations to S 2 due to: 1. Electroluminescence gain (proportional) 2. Light Collection Efficiency & PMT quantum efficiency (5 -20% typical) Xenon Gain 31. 4 sigma 7. 5 MPGD 2013, Zaragoza July 2 nd, 2013 Xenon Gain 31. 4 sigma 7. 5 M. Alfonsi 6

Digital readout with pixels • Counting the number of hit pixels MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 7

Digital readout with pixels • Counting the number of hit pixels • Caveat: 1. Every electron in a different hole 2. 100% single electron detection efficiency • (1) depends on pixel pitch and diffusion along the drift distance in the vapor phase. • Toy MC for the case of xenon (diffusion coefficients from Garfield/Magboltz) MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 7

Pixel pitch & diffusion in xenon Pressure 1. 0757 bar absolute • 10 k. V, 55µm pixel pitch, 1. 0 cm path MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 8

Pixel pitch & diffusion in xenon Pressure 1. 0757 bar absolute • 10 k. V, 55µm pixel pitch, 1. 0 cm path • 10 k. V, 55µm pixel pitch, 3. 0 cm path MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 8

Pixel pitch & diffusion in xenon Pressure 1. 0757 bar absolute • 10 k. V, 55µm pixel pitch, 1. 0 cm path • 10 k. V, 55µm pixel pitch, 3. 0 cm path • 2 k. V, 55µm pixel pitch, 1. 0 cm path MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 7

Pixel pitch & diffusion in xenon Pressure 1. 0757 bar absolute • 10 k. V, 55µm pixel pitch, 1. 0 cm path • 10 k. V, 55µm pixel pitch, 3. 0 cm path • 2 k. V, 55µm pixel pitch, 1. 0 cm path, 95% efficiency MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 7

Application to large area dual phase TPC ? MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 9

Large Area dual phase TPC? MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 10

Large Area dual phase TPC? • Maybe! • Recent production on 8” wafers prospects industrialization and large volume at reduced cost. MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 10

A small-size high-impact application MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 11

Light & charge yield in xenon • The response of the medium, i. e. the scintillation light (Ly) and the ionisation charge (Qy) yield, must be measured for electronic and nuclear recoils Scheme from Manzur et al. , Phys. Rev. C 81 (2010) 025808 MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 12

Light & charge yield in xenon • The response of the medium, i. e. the scintillation light (Ly) and the ionisation charge (Qy) yield, must be measured for electronic and nuclear recoils From G. Plante et al. , ar. Xiv: 1104. 2587 MPGD 2013, Zaragoza July 2 nd, 2013 Adapted from Manzur et al. , Phys. Rev. C 81 (2010) 025808 M. Alfonsi 12

Ly & Qy measurements Dedicated measurements: • neutron elastic scattering for nuclear recoils • Compton scattering for electronic recoils • small size noble liquid target detector θ Neutron / Gamma generator MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 13

Ly & Qy measurements Dedicated measurements: • neutron elastic scattering for nuclear recoils • Compton scattering for electronic recoils • small size noble liquid target detector θ Neutron / Gamma generator Systematic uncertainty from the unknown position within target or double scatters. Ø Grid. Pix adds high resolution position reconstruction and digital charge readout! MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 13

Xe TPC @ Nikhef MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 14

Measurements with Grid. Pix MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 15

Cryogenic robustness MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 16

New geometries under test New geometries for the dykes (the “perimeter support” for the mesh). Pillars with additional extended structures. (NIM A 718 (2013) 446 -449) Dummy wafers (full anode instead of Timepix) under test. MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 17

Pure nobles gasses • Measurements at CERN in 2011 in a gaseous and dual phase argon TPC • Measurements at Nikhef in a gaseous argon or xenon TPC Nikhef CERN 2011 MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 18

Pure noble gasses • Stable operation with a reasonable charge amplification only with non ultra-pure gas (e. g. industrial standard argon 99. 997%). • With argon 99. 9999% or xenon 99. 999% we observe a sharp transition between a too small gas amplification region and the discharge regime MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 19

Future plans MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 20

Towards full ceramics • Full ceramics devices under study: – Si. O 2 as insulator – Si-rich Si 3 N 4 as the resistive material • Matching thermal expansion properties • Low Outgassing and high radiopurity MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 21

Towards full ceramics • Full ceramics devices under study: – Si. O 2 as insulator – Si. RN is the resistive material • Matching thermal expansion properties • Low Outgassing and high radiopurity • A resistive grid can limit the charge available for a spark to only one cell. • An embedded conductive network can distribute voltage uniformly MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 21

In the meanwhile… • A more sensitive pixel electronics would be helpful • Recent literature keeps emphasizing that closed structure and confined amplification region are the key of success • Producing and testing Grid. Pix with any GEM-like or other specific amplification structure can be time / money consuming • “Test the water” placing the amplification structure very close to a bare Time. Pix • Investigate some specific quencher that does not spoil the scintillation signal MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 22

Thanks for your attention! MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 23

Spare slides MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 35

CERN 2011 In collaboration with the ETH Zurich: - gaseous warm / cold argon TPC. - dual phase argon TPC. IEEE NSS-MIC Conf. Rec. 2011, 92 -98 MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 36

CERN 2011: cold argon gas Average waveform (A. U. ) The amplification of the Grid. Pix can be verified with the light detected by PMT. MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 37

MPGD 2013, Zaragoza July 2 nd, 2013 Average waveform (A. U. ) CERN 2011: cold argon gas M. Alfonsi 38

MPGD 2013, Zaragoza July 2 nd, 2013 M. Alfonsi 39