B.K. Singh Banaras Hindu University (India) 24-Nov-17 DST SERC EHEP SCHOOL (Nov 7-27, 2017)

Transcription

1 B.K. Singh Banaras Hindu University (India)

2 Outline: Vacuum based photon detectors (PMT, MCP-PMT, HPD, HAPD) -History, basics, Tools, Basic properties Photo-Emissive materials -Techniques, Types, QE, Spectral sensitivity New Technology (Additive 3 D printer) Summary

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4 Photomultiplier tube (PMT): Principle of operation:

5 Types of Dynode configuration : PMT with Metal foil dynodes: Other type of Dynodes: Box-and-grid Grid Circular Cage Line focusing Venetian blind Fine mesh

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9 Collection efficiency (CE) and detection quantum efficiency of a PMT

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11 Technology of photocathodes: PHOTOCATHODES: processing under vacuum and detector assembly & operation under gas substrate preparation PC deposition & quality evaluation PC transfer & storage detector assembly, operation & evaluation Requirements for large PCs good flatness & stiffness high & reproducible QE on large area no contact with humidity, Oxygen etc during its full lifetime Photodetector must be leaktight (as should be all utilities) Need state of the art technologies: - vacuum technology - multi-source thin film coating - quality evaluation - in situ encapsulation - cleanroom facilities

12 Spicer s three step model Photoemission process is divided into three steps: Photon absorption/photoexcitation Transport of electrons towards surface Electron escape into the vacuum Ref: W.E. Spicer, Phys. Rev. 112 (1958) 114.

13 Modes of Operation Reflective Transmissive Semi-transparent CsI Substrate Reflective CsI Substrate Transmissive CsI Substrate Semitransparent

14 Positive Electron Affinity (PEA) to Negative Electron Affinity (NEA) photocathodes:

15 PC substrate preparation 1. Customised technology for PC elements - PC substrate: printed circuit board - FEE connectors - Grounding shield plate - Single piece frame with stiffening cross-bars deformation pad pcb ~5 m / mbar P ALICE/HMPID 50 PCs total area 11 m 2 2 pcb s pad plane frame 2. Customised method to glue pcb s: Vacuum table - minimise use of glue - keep PC substrates clean during all production manoeuvres pollution/outgassing may give problems later: bad for CsI coating (bad CsI QE) long vacuum pumping cycle due to outgassing (RGA) risk to pollute the vacuum evaporator setup grounding plate (double sided pcb) Printed circuit boards: Substrate for CsI! CsI Previous technology single layer pcb (STAR/COMPASS) Today s technology double layer pcb, implicit leaktight 3. customised cleaning procedure - ultra-sonic bath & detergents - ultra-sonic bath & demi-water - rinsing with pure alcohol - dry & hot air oven Gold plated Ni/Cu pads (typical ~8x8mm 2 )

16 BHU Thermal deposition set up for UV photocathodes: Thickness/Rate Monitor Main Chamber Load Lock Chamber Vac. Gauge Monitor Electronic Control unit For TMP SRS RGA 300 amu with control unit and filament Current Control Unit View Port Step Down transformer Dry Pump Tantalum Boat

17 BHU absolute QE measurement setup: PMT or Sample Photocathode +50V A Anode/Dynode chain photocathode Current limiting Resistor Circuit diagram for photocurrent measurement O Ring Based 63 flange O ring Groove MHV and BNC Cu Plate to hold the sample 234/302 VUV MONOCHROMATOR (110 nm-400 nm)

18 A Schematic view of BHU absolute QE measurement setup: Model 632 Deuterium Light Source Focusing Elbow Photocathode/PMT PMT Reflecting Mirror Slit Rotating grating Al coated MgF2 pick- off mirrors Collimating Mirror Mechanical counter TMP/Dry pump

19 CERN Photocathode deposition plant (bldg 3 CERN) Deposition rate monitor External heating T=65 C Witness sample PC computerised monitoring & control 4 sources + shutters Remote controlled encapsulation/ protection box

20 CsI QE QE of ALICE HMPID large area CsI PCs evaluated with test-beam data E [ev] 6.0 QE(170) increase by ~35% CERN (PC38) previous PC production technology ( 1999) CERN (PC37) CERN (PC39) CERN (PC34) CERN (PC35) CERN (PC33) STAR (PC32) 0.05 The curves give the QE for the full CsI-PC surface, i.e. assuming that the full PC (60x40 cm 2 ) as active area [nm]

21 CsI QE Large area PCs vs small samples (fully metallic, i.e. no pads) small samples (high photon flux) Seguinot TU Munich 0.40 Wzm. Inst. (RD26 Ref.) large area PCs (single photons) HADES Av. CERN Av QE(CERN) QE(HADES) [nm] 1. HADES applies different CsI PC production technology but obtains equivalent results Hades: carbon substrate & CsI tablet & e gun CERN: Gold substrate & CsI pre-melted powder & evaporation by Joule effect

22 Absolute QE measurement of Cesium Iodide photocathode at BHU:

23 UV and visible sensitive photocathodes: Data from Hamamatsu Photonics, Japan Data from Weizmann Detector Group, Israel Cs 2 Te Bi-alkali Multi-alkali Extended Red multi-alkali

24 Quantum Efficiency (% ) Super/Ultra bialkali and NEA Photocathodes: Quantum efficiency (%) Ultra bi-alkali UBA Super bi-alkali SBA Data from Hamamatsu Photonics, Japan UBA GaAsP GaAs 10 Conventional Wavelength (nm) Wavelength (nm)

25 Quantum Yield of alkali, bialkali, multialkali and NEA photocathodes:

26 Response time and Quantum Yield of photocathodes: Materials Dominant mode of scattering Eq. for response time (τ) Estimated range of τ (sec) Typical yield (p.e/photon) Metals Electron-electron τ= L/νa to x10-5 to 0.4x10-4 Semiconductors & insulators Electron-lattice τ= (Ek/ΔEp)(Ip/νa) to to 0.25 (0.40) Negative electron affinity (NEA) Electron-lattice (thermal diffusion of electrons in CBM) τ=q L D /µƙt 2x10-10 to 7x to 0.7 L= Electron path length. νa = Average speed of electron over its complete trajectory. EK = Energy above the surface vacuum level Ep =Average energy loss per collisions. lp = electron-phonon scattering length. LD = Electron diffusion length. µ = Electron mobility. q = Electron charge.

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34 Photon ageing on CsI photocathode (In vacuum): B.K. Singh et al., Nucl. Instr. Meth. A 610 (2009) Nov-17 DST SERC EHEP SCHOOL (Nov 7-27, 2017)

35 Surface characterization study after photon ageing: Atomic Force Spectroscopy (AFM) study Scanning Electron microscopy (SEM) study B.K. Singh et al., Nucl. Instr. Meth. A 610 (2009)

36 Types of Dynode configuration : PMT with Metal foil dynodes: Other type of Dynodes: Box-and-grid Grid Circular Cage Line focusing Venetian blind Fine mesh

37 Microchannel Plate (MCP) based photon detector: Advantages: Good spatial resolution Excellent time resolution (50 ps FWHM) Magnetic field operation possible Disadvantage: Short life time (photocathode degradation due to the residual gas) Remedy: Chevron configuration of two MCPs & Protective Al foils between the photocathode and 1 st MCP or in the gap between the two MCPs See for details: & Philips Photonics

38 (x10 5 ) Fabrication process of MCP and some preliminary results (Large Area Picosecond photo Detector US Project): Resistive coating using ALD (20 nm) Apply emissive layer of Al2O3 Apply conductive layer for HV by thermal evaporation technique

39 Hybrid Photon detectors: Hybrid Avalanche Photodiode (HAPD) Hybrid Photodiode (HPD) QUASAR (Other hybrid photodetector) C. Joram/CERN

40 Hybrid Photodiodes (HPD) Design: A. Proximity Focusing HPD: C. Fountain Focusing HPD: (Similar to Cross focusing HPD) Compact Limited photosensitive area Highly B-field tolerant B. Cross Focusing HPD: High resolution imaging Cross focusing helps for strong demagnification Large distance between cathode & Silicon sensor Sensitive to magnetic field C. Joram/CERN

41 Si-based Photomultiplier (Si PM): Time response of a Si PM: Neutron bombardment

42 Visible light photon counter (VLPC) Si Photomultiplier (Si PM) Hybrid Avalanche Photo-detector (HAPD) Single photon counting

43 Gas Based Detectors

44 Brief history of Gaseous detectors:

45 Gaseous photon detectors: photoelectron production Figure :Photoelectron production via a photo- Sensitive gas mixture or by a solid photocathode. Figure: Typical wire chamber (MWPC) based Geometry with a solid photoconverter.

46 From MWPC to Micro-pattern detector: Electron multiplication Multiwire Proportional Chamber Microstrip Gas Chamber Typical cell size>1 mm GEM/THGEM μcat, μgroove, μdot Micromegas Typical cell size ~ 100μm Due to small dimensions, Streamers develop easily into sparks!

47 GEM Etching Technology..(CERN) GEM are being made now by various techniques such as laser based etc.

48 GEM AND THGEM: Chechik et al. NIM A535 (2004) 303 Shalem et al. NIM A558 (2006) 475 Manufactured by standard PCB techniques of precise drilling in G-10 (+ other materials) and Cu etching. ECONOMIC & ROBUST! Standard GEM 10 3 gain in single-gem THGEM 10 5 gain in single-tgem A Breskin/weizmann Hole diameter d=0.3-1 mm Distance between holes a=0.7-7 mm Plate thickness t=0.4-3 mm 0.1mm 1mm F. Sauli (CERN) Cu G mm rim: prevents discharges high gains!

49 THGEM.. A new device which has to be studied!

50 Multiplication of electrons induced by radiation in gas or from solid converters (e.g. a photocathode) Reflective photocathode Semi-transparent photocathode E drift E Hole E trans Multiplication inside holes reduces secondary effects. (No Photon feedback) THGEMs screen the photocathode

51 GEM Performance

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55 MICROMEGAS Performance

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57 Application to physics experiments

58 GEM-based thermal neutron beam monitors for spallation sources: G. Croci et al., NIM A732 (2013) 217. Triple GEM detectors with a solid state thermal neutrons converter cathode. Histogram of events counting rate in one run. Protons current and GEM events Counting rate as a function of time.

59 PHENIX HBD BNL -CsI coated directly on GEM -CF 4 gas as radiator -Reverse drift field (Hadron blind) -Proximity focussing geometry (leptons produce a blob of 35 photons in about 10 cm 2 ) ALICE/HMPID concept of CsI RICH - liquid C 6 F 14 radiator - proximity focussing geometry - small gap MWPC (~2 mm) - cathode pads coated with CsI MWPC front-end electronics pad cathode covered with CsI film NA44 / CERN (0.3 m 2 ) finished STAR / BNL (1 m 2 ) finished PHENIX / BNL (0.7 m 2 ) finished HADES / GSI (1.5 m 2 ) finished Experiments with CsI RICH (active area m 2 ) ALICE / CERN (11m 2 ) running COMPASS / CERN (5.8 m 2 ) running

60 Hadron Blind Detector (PHENIX Experiment at BNL, US) e - Cherenkov photons E-field photo electron avalanche electrons primary ionization R/O Pad To detect Cherenkov radiating electrons: Deposit 350 nm CsI photocathode layer on top GEM Electron radiates Cherenkov light in CF 4 Photoelectrons follow field lines through GEM holes to avalanche region Primary ionization in drift gap is swept towards mesh in RB E-field 3-stage avalanche leads to gain between

61 X-ray imaging: Radiology and diagnostics:

62 Scintillation light imaging:

63 Time Projection Chamber Polarimeter NASA Concept: Fig. 1: The time projection polarimetry uses a simple strip anode to form pixelized image of photoelectron tracks. Fig. 2a: The TPC forms an image by digitizing the signal on each anode strip. Signal proportional to the charge deposited on each strip are shown on the left. Fig. 2b: The resulting image on the right shows the interaction point, emission angle, and end of the track. Each circle has a size proportional to the deposited charge in each virtual pixel.

64 THGEM immersed in LXe: First electroluminescence events - Gammas May S2 S1 THGEM 2.5 kv Etop = 0, Edrift = 1 kv/cm S1 S2 THGEM 3.0 kv Etop = 0, Edrift = 1 kv/cm ETHGEM~70kV/cm THGEM: t=0.4, d=0.3, a=1, h=0.1

65 THGEM immersed in LXe: Alphas July 4, 2013 (RD 51 Collaboration 2013) S1 S2 ETHGEM~70kV/cm S1 S1 S2 S2

66 First observation of electroluminescence in liquid Xe within THGEM holes: Modest charge multiplication + Lightamplification in sensors immersed in the noble liquid, applied to the detection of both scintillation UV-photons (S1) and ionization electrons (S2). S1 UV-photons impinge on CsI-coated THGEM electrode; extracted photoelectrons from CsI are trapped into the holes, where high fields induce electroluminescence (+ possibly small charge gain); resulting photons are further amplified by a cascade of CsI-coated THGEMs. Similarly, drifting S2 ionization electrons are focused into the hole and follow the same amplification path. Prompt S1 and delayed S2 signals are recorded optically by an immersed GPM (or PMT, ) or by charge collected on pads.

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68 GEM for Plasma Diagnostics:

69 GEM Detector Development for CBM experiment at FAIR (A. K. Dubey et al.) 4 m 7.5 λ I low-mass vector meson measurements (compact setup)) Muon Detection System (MUCH) Fe μ Challenges for muon detection: high rate capability ( up to 1MHz/cm2) high granularity (up to 1 hit/cm2 in central Au-Au colisions) Good position resolution Should be radiation resistant Large area detector modular Data to be readout in a self triggered mode GEM for the first few stations. shielding 13.5 λ I μ + Alternating layers of absorbers and detector triplets(muon Chambers)

70 Using conventional electronics GeV/c Muons (V1+V2+V3)=1048 volts We have built and tested several multi GEM prototypes at VECC. Charged particle detection efficiency of > 95% has been obtained using cosmic muons. Have tested the response of the chambers to MIPs using pion/muon beams at CERN and also with protons at GSI and COSY in a self triggered mode and using CBM DAQ. An Efficiency ~95 % is observed. More detailed analysis is underway. Next Steps: -- Building and testing a large size GEM (30 cm x 30 cm). -- Solving issues concerning design, stretching/gluing, optimizing jigs, etc., Radiation test with neutrons at VECC facility. -- Testing of rate capability using the X-ray source. FEE a new 68 channel ASIC similar to nxyter is under consideration. Using self triggered FEE, nxyter

71 Airport Security

72 New Technology

73 AMAZE (Additive Manufacturing Aiming Towards Zero waste & Efficient production of high tech metal products): Considered the third industrial revolution among manufacturers, 3D printing builds a solid object from a series of layers, each one printed on top of the last also known as additive manufacturing. AMAZE aims to put the first 3D metal printer on the International Space Station (ISS) allowing astronauts to produce tools and new structures on demand. manufacturing in space could save huge amounts of time and money. 20 million funding from ESA and EU; with 28 industrial and institutional partners across Europe.

74 Amaze researchers have already begun printing metal jet engine parts and aeroplane wing sections up to 2m in size. These high-strength components are typically built from expensive, exotic metals such as titanium, tantalum and vanadium. AMAZE has the potential to produce almost "zero waste ; Printing objects as a single piece - without welding or bolting - can make them both stronger and lighter. Fig: Hinges for the Airbus A320 - conventional (background) and 3D printed (foreground). Computer-aided design software determines shape of 3D model using cross-sections. Laser etches the shape of cross-section into metal powder and heats it so it solidifies and creates a solid layer. More powder is spread to create the next layer and so on until the 3D object is created. By leaving one non-solid layer in between, interlocking structures can be created. The 3D printing materials market will be worth in excess of $600m by 2025.

75 3D printers used to build Robohands to help the fingerless: After losing his fingers in a woodworking accident, South African Richard Van As joined up with Ivan Owen, a theatrical prop designer from the US, to design a new, working hand using a 3D printer. Markerbot, which donated a Replicator 2 to each of them so they could work together on prototypes even though they were thousands of miles apart.

76 Thank You

77 Si Photodiode Gain= 1 QE~ 100% Extremely stable Large dynamical range