Colloquium Nikhef, July Particle detector de- velopment in various fields of physics Serge Duarte Pinto Gaseous Particle detector development in various fields of physics detectors Ionization Drift, multiplication Induction Serge Duarte Pinto Gem s Large gem s Single mask PHOTONIS technique Splicing Prototype July Spherical gem s Di ff raction Prototype Tooling Beam instrumen- tation Robust triple gem
Gaseous detectors Working principle Particle detector de- velopment in various fields of physics Serge Duarte Pinto Gaseous multiwire single wire strips holes parallel plate grooves detectors Ionization Drift, multiplication Induction Working principle of microhole & strip plate Cobra thick bulk Micromegas gem Gem s all gaseous detectors Large gem s Ionization Single mask technique Drift Splicing Prototype 50 µm Multiplication Spherical gem s Charge Di ff raction Prototype collection/ signal micropin array µ - InGrid on pixel chip fi ne-pitch pic gem Tooling induction Beam instrumen- tation Robust triple gem
Ionisation Charged and neutral particles Particle detector de- velopment in various fields of physics Serge Duarte Pinto 0 10 [mm] 20 Ionization mechanisms Gaseous detectors Charged particles: tracks, clusters Ionization Drift, Primary ionization multiplication Secondary ionization Induction Penning transfer Gem s Neutral particles (photons, neutrons): conversion process Large gem s Single mask X-rays: heavy noble gases (Kr, Xe) technique Neutrons: special isotopes ( He, B) Splicing Prototype Isotopes used for thermal neutron detection Spherical gem s Di ff raction Isotope σ (barn) Reaction Prototype Tooling He . · He + n → H( . MeV) + p( . MeV) Beam Li . · Li + n → H( . MeV) + α ( . MeV) instrumen- tation B . · B + n → Li( . MeV) + α ( . MeV) Robust triple gem
Drift & multiplication Movement and multiplication of charges Particle detector de- Drift velopment in various fields of Electrons: high drift velocity and strong di ff usion: physics Serge � DL Duarte σ x = (L is the drift length) Pinto µ E Gaseous Ions: follow electric field lines, but ∼ × slower detectors Ionization Drift, multiplication Multiplication Induction Strong electric fields, ∼ kV/cm and Gem s more Large gem s Single mask Only electrons make ionizing collisions technique Splicing The avalanche develops exponentially: Prototype Spherical � b gem s N Di ff raction = exp α ds N Prototype a Tooling ( α is the first Townsend coe ffi cient ) Beam instrumen- tation Proportional mode (energy resolution) Robust triple gem
Collection & induction Signals induced by movement of charges Particle detector de- Induction velopment in various fields of All charges are absorbed by electrodes, or recombine. physics Only movement of charges causes signal induction. Serge Duarte Ramo’s theorem: Pinto I ind n (t) = –q E n [ x (t)] · v (t). Gaseous detectors E n is the weighting field . Ionization Drift, Wire chamber signals are dominated by slow movement of ions multiplication (the so-called ion tails ). Induction Gem s The case of resistive readout electrodes is more complicated Large gem s (the weighting field becomes time dependent). Single mask technique Splicing Prototype Spherical gem s Di ff raction Prototype Tooling Beam instrumen- tation cartesian small angle hexaboard strips-on-pads Robust triple gem
Gem s Gas Electron Multiplier Particle detector de- Gem properties velopment in various fields of Amplification structure independent from physics readout structure Serge Duarte Fast electron signals, no ion tails Pinto Manufacturing based on industrial materials Gaseous detectors & procedures Ionization Drift, Possibility to cascade multiplication Induction Flexible material, possible to change shape Gem s Large gem s Ions Single mask technique Splicing Prototype Spherical gem s Di ff raction 40 % Prototype Tooling Beam 60 % instrumen- tation Electrons Robust triple gem
Gem s Discharge probability Particle detector de- Cascading gem s suppresses discharge probability velopment in various fields of physics Serge Duarte Pinto Gaseous detectors Ionization Drift, multiplication Induction Gem s Large gem s Single mask technique Splicing Prototype Spherical gem s Di ff raction Prototype S. Bachmann et al Nucl. Instr. and Meth. A S. Bachmann et al, Nucl. Tooling ( ) Instr. and Meth. A Beam instrumen- ( ) tation Robust triple gem
Large area GEMs For muon tracking and triggering Particle detector de- velopment in various Ideas for a totem T upgrade fields of physics Large triple gem chambers ( ∼ cm ) Serge Duarte Discs of × chambers, back to back Pinto Overlap allows adjustable disc radius Gaseous detectors Ionization Drift, multiplication Induction Gem s Large gem s Single mask technique Splicing Prototype Spherical gem s Di ff raction Prototype Tooling Beam instrumen- tation Robust triple gem
TOTEM T upgrade Technical challenges for such large active area Particle detector de- velopment Technical hurdles for fabrication of large gem s in various fields of Double mask technique introduces alignment errors at such physics dimensions Serge Duarte Pinto Base material is only mm wide Gaseous detectors Ionization Drift, multiplication Induction Gem s Large gem s Single mask technique Splicing Prototype Spherical gem s Di ff raction Prototype Tooling Beam instrumen- tation Robust triple gem
TOTEM T upgrade Technical challenges for such large active area Particle detector de- velopment Technical hurdles for fabrication of large gem s in various fields of Double mask technique introduces alignment errors at such physics dimensions − → use single mask technique Serge Duarte Pinto Base material is only mm wide Gaseous detectors Ionization Drift, multiplication Induction Gem s Large gem s Single mask technique Splicing Prototype Spherical gem s Di ff raction Prototype Tooling Beam instrumen- tation Robust triple gem
TOTEM T upgrade Technical challenges for such large active area Particle detector de- velopment Technical hurdles for fabrication of large gem s in various fields of Double mask technique introduces alignment errors at such physics dimensions − → use single mask technique Serge Duarte Pinto Base material is only mm wide − → splice foils together Gaseous detectors Ionization Drift, multiplication Induction Gem s Large gem s Single mask technique Splicing Prototype Spherical gem s Di ff raction Prototype Tooling Beam instrumen- tation Robust triple gem
Large GEM manufacturing Double mask vs. single mask technique Particle detector de- velopment in various fields of Single mask Double mask physics µ m kapton foil Serge Duarte µ m copperclad Pinto photoresist coating, Gaseous detectors masking, exposure Ionization Drift, metal etching multiplication Induction Gem s kapton etching Large gem s Single mask technique metal etching Splicing Prototype Spherical second masking gem s Di ff raction metal etching, Prototype Tooling and cleaning Beam instrumen- tation Robust triple gem
Single mask technique Similar performance at lower cost Particle detector de- First results were not encouraging − → velopment in various SMT now performs similar to standard gem . fields of physics delamination Serge Duarte Pinto Gaseous detectors Ionization Single GEM gain curves Drift, 1000 multiplication Induction SMSC010 Gem s SMSC011 Large gem s SMSC012 SMSC013 Single mask SMSC014 technique Splicing 100 gain Prototype Spherical gem s Di ff raction Prototype Tooling Beam 10 instrumen- 350 400 450 500 550 600 tation Δ V GEM (V) Robust triple gem
Large GEM manufacturing Back to biconical holes Particle detector de- velopment Evolution of single-mask technique results in biconical holes in various fields of physics polyimide etching top view Serge Duarte Pinto Gaseous bottom view detectors bottom metal etching Ionization Drift, multiplication Induction bottom view Gem s photoresist stripping Large gem s Single mask technique Splicing Prototype cross-section Spherical polyimide etching gem s Di ff raction Prototype Both visually and in terms of performance these gem s are almost Tooling Beam indistinguishable from standard gem s. instrumen- tation Robust triple gem
Splicing GEMs Glue foils with pyralux coverlay Particle detector de- velopment in various fields of physics Serge Duarte Pinto Gaseous detectors Ionization Drift, Coverlay to glue gem s multiplication Induction Seam is flat, regular, mechanically Gem s and dielectrically strong, and only Large gem s mm wide. Single mask technique Splicing Prototype kapton glue flash gap Spherical gem s − → Di ff raction Prototype Tooling Beam instrumen- tation Robust triple gem
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