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Signal formation for energy, time and position measur

Advanced FEE solutions for large arrays of semiconductor detectors. Signal formation for energy, time and position measurements Segmented detectors; - advanced FEE for Ge Detectors Briefly, some specific issues and cases:

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Signal formation for energy, time and position measur

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  1. Advanced FEE solutions for large arrays of semiconductor detectors • Signal formation for energy, time and position • measurements • Segmented detectors; - advanced FEE for Ge Detectors • Briefly, some specific issues and cases: • ◦ MINIBALL & AGATA (& GRETINA) FEE for gamma rays • (CERN-Isolde & EU Tracking Array -LNL; GSI; Ganil) • ◦ LYCCA & TASISpec FEE for particles • (GSI -Calorimeter & Superheavy Element Spectroscopy) G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012 Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest

  2. a) Signal formation for energy, time and position • measurements, • (we’ll limit our attention to capacitive & segmented detectors) • b) Related issues in segmented detectors • - dynamic range • - high counting rates • - induced signals & crosstalk - pros vs. conts • c) AGATA & MINIBALL – advanced FEE solutions • - Dual Gain CSP - for the central contact • - ToT method ( - combined dynamic range ~100 dB, up to 170 MeV) • - Transfer function, Induced signals, Crosstalk • - Applications: - Impurities concentration measurement; • - Cosmic ray direct measurement up to 170MeV equiv. gamma • LYCCA & TASISpec - FEE for DSSSD G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012 Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest

  3. A typical structure of a segmented, tapered and encapsulated, HP-GeDetector [- HV] (GND) + HV (~ kV/cm) Rp Ci (-) Central contact (Core) (- e ~ mm) Exterior contacts (N Segments) (+) - Qi N = 6; 12; 18; 28; 36 • Standard n-type • Intrinsic HP-Ge (P-I-N) • Closed end • Coaxial structure • Io ~ < 100 [pA] • Cdet ~ 30 - 45 pF • Collection time ~ 30 - 1000 ns

  4. FFEFEE [HP-Ge + CSP] +Analog Nuclear Electronics Spectroscopic Chain is used in order to extract the: E, t, position (r, azimuth) Fast pipeline ADC [DGF] FEE Fast Pipe line ADC [DGF] Analog E+T Filter Amplifier Chain Collected charge pulses (+ &-) Qd - delta t UCSP – exponential Pile-up of pulses t Digital Filters (Fast, Slow) UFA ~ Gaussian t Baseline restorer

  5. [HP-Ge + CSP] +Digital Nuclear Electronics Spectroscopic Chain is used in order to extract the: E, t, position (r, azimuth) Fast pipeline ADC + PSA FEE Fast pipeline ADC & [DGF] Digital Filters [for Trigger, Timing, Energy, Position] Collected charge pulses (+ &-) Qd - delta t UCSP – exponential Pile-up of pulses t Digital Filters (Fast, Slow) UFA ~ Gaussian t Baseline restorer

  6. + Rp - Detector Detector Signal Collection • a gamma ray crossing the Ge • detector generates electron-hole pairs • charges are collected on electrode • plates (as a capacitor) building up • a voltage or a current pulse Z(ω) • Final objectives: • amplitude measurement(E) • time measurement (t) • position(radius, azimuth) Electronic Circuit Which kind of electronic circuit ; Z(ω)?

  7. Z(ω) Rp + - Electronic Circuit Detector Detector Signal Collection ifZ(ω) is high, • charge is kept on capacitor nodes and a voltage builds up (until capacitor is discharged) • Advantages: • Disadvantages: if Z(ω) is low, • charge flows as a current through the impedance in a short time. • Advantages: • Disadvantages: • limited signal pile up (easy BLR) • limited channel-to-channel crosstalk • low sensitivity to EMI • good time and position resolution • excellent energy resolution • friendly pulse shape analysis position • channel-to-channel crosstalk • pile up above 40 k c.p.s. • larger sensitivity to EMI • signal/noise ratio to low worse resolution

  8. Charge Sensitive Preamplifier • Active Integrator(Charge Sensitive Preamplifier -CSP) • Input impedance very high ( i.e. ~ no signal current flows into amplifier), • Cf/Rffeedback capacitor /resistor between output and input, • very large equivalent input dynamic capacitance, • sensitivityor~(conversion factor) A(q) ~ - Qi/ Cf • large open loop gain Ao ~ 10,000 - 150,000 • clean transfer function (no over-shoots, no under-shoots, no ringing) (Rf.Cf ~ 1ms) Ci ~ “dynamic” input capacitance tr~ 30-1000ns) - Qi Step function R f o Invert ing - Ao • Ci ~ 10 - 20,000 pF • ( up to 100,000) “GND” Non- Inv. + jFET GND Charge Sensitive Stage (it is a converter not an amplifier)

  9. Pole - Zero cancellation technique Rf . Cf ~ 1 ms Cf~ 1pF (0.5pF-1.5pF), Rf ~ 1GOhm Rd . Cd ~ 50 µs simpledifferentiation without Rpz Rpz~ 20 k Ohm Baseline shifts if (RfCf)= (Rpz .Cd) and RdCd ~ 50 µs differentiation with P/Z adj.  no baseline shifts with Rpz Cd~ 47 nF, Rd~1.1 kOhm Baseline restored

  10. Pole - Zero cancellation technique Rf . Cf ~ 1 ms Cf~ 1pF (0.5pF-1.5pF), Rf ~ 1GOhm Rd . Cd ~ 50 µs simpledifferentiation without Rpz Rpz~ 20 k Ohm Baseline shifts if (RfCf)= (Rpz .Cd) and RdCd ~ 50 µs differentiation with P/Z adj.  no baseline shifts with Rpz Cd~ 47 nF, Rd~1.1 kOhm Baseline restored

  11. Pole - Zero cancellation technique Rf . Cf ~ 1 ms Cf~ 1pF (0.5pF-1.5pF), Rf ~ 1GOhm CSP Rd . Cd ~ 50 µs simpledifferentiation without Rpz R pz ~ 21 k Ohm Baseline shifts if (RfCf)= (Rpz .Cd) and RdCd ~ 50 µs - clean differentiation with P/Z adj.  no baseline shifts with Rpz Cd ~ 47 nF, Rd ~1.1 kOhm Baseline restored

  12. This is only the ‘hard core’ of the CSP stage • (ChargeSensitivePreamplifier) but the FEE • must provide additional features: • a P/Z cancellation (moderate and high counting rate) • a local drive stage (to be able to drive even an unfriendly • detector wiring !) • (opt.) an additional amplifier (but with Gmax.~ 5) • (N.B. a “free advice”: … never install an additional gain • in front of the ADC ! -namely, after the transmission cable !) • a cable driver (either single ended –coax. cable or • differential output - twisted pair cable) Any free advice is very suspicious ( anonymous quote ) G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012 Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest

  13. Block diagram of a standard CSP (discrete components and integrated solution… - what they have in common ) (alternatives) (alternatives) (+) Optionally with cold jFET (-) Warm part (outside cryostat) Cold part (cryostat) (alternatives) G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012 Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest

  14. Block diagram of a standard CSP (discrete components and integrated solution… - what they have in common ) (alternatives) (alternatives) (+) Optionally with cold jFET (-) Warm part (outside cryostat) Cold part (cryostat) • tr 25 ns ( 1 - 200 ) ns • tf 50 μs ( 10 - 100 ) μs • CSP- ‘gain’  50 mV / MeV (Ge) • (10-500 mV / MeV) (alternatives) G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012 Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest

  15. tr~ 30-40 ns Ch.1 @ 800 mV - no over & under_shoot IF1320 (IF1331) (5V; 10mA)& 1pF; 1 GΩ also GRETINA Eurysis warm • Warm & cold jFET • DGF-4C(Rev.C) G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012 Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest

  16. AGATA τopt~ 3-6 µs J.-F. Loude, Energy Resolution in Nuclear Spectroscopy, PHE 2000-22, Univ. of Lausanne • the equivalent noise • charges Qn assumes • a minimum when the • current and voltage • contributions are equal • current noise ~ (RC) • voltage noise ~ 1/(RC) • ~ Cd 2 • 1 /fnoise ~ Cd2

  17. Dynamic range issue (DC - coupled) • Factors contributing to saturation: • Conversion factor – ( step amplitude / energy unit [mV/MeV] ); • Counting rate [c. p. s.] and fall time; • The allowed Rail-to-Rail area [LV-PS] {(+Vc - Vc) – 2xΔf -2δFilt.} +Vc (+ Rail ) DC – unipolar (-) Saturation (+Vc) δFilter A(q) ~ - Qi/ Cf Δf+ ( forbidden region ) Linear range DC - bipolar DC coupled channel Δf- Saturation (-Vc) DC – unipolar (+) -Vc (- Rail) G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012 Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest δFilter

  18. Dynamic range issue (AC - coupled) • Factors contributing to saturation: • Conversion factor – ( step amplitude / energy unit [mV/MeV] ); • Counting rate [c. p. s.] and fall time; • The allowed Rail-to-Rail area [LV-PS] {(+Vc - Vc) – 2xΔf -2δFilt.} +Vc (+ Rail ) Saturation (+Vc) δFilt A(q) ~ - Qi/ Cf Δf+ ( forbidden region ) AC -Unipolar (negative) Linear range AC -Unipolar (positive) BL shift Δf- AC coupled channel Saturation (-Vc) -Vc (- Rail) G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012 Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest

  19. What to do to avoid saturation? Conts(“price”) • to reduce the “gain” Resolution ( Cf larger ) • to fix the base line asymmetric if DC coupled (expand:F~2), • but for AC ? (expand only: F~ 1.5)! • to reduce the fall time  Resolution ( Rf smaller ) • (OK only for high counting rate limitation) • to reduce the fall time, how ? • passively(smaller tf) Resolution ( Rfsmaller ) • linear active fast reset • in the 2. stage  ToT 2.nd stage ( <10 -3) • (GP et al, AGATA- FEE solution) • in the first stage ToT 1.st stage ( <10 -3 ??) • (not yet tested for high spectroscopy) • (G. De Geronimo et al, FEE for imaging detectors solution • A. Pullia, F. Zocca, Proposal for HP-Ge detectors) G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012 Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest

  20. Potential solutions for active reset @1st stage a) & b)  for sequential reset c) through g)  for continuous reset G. De Geronimo, P. O’Connor, V. Radeka, B.Yu; FEE for imaging detectors, BNL-67700

  21. a) Custom designed vs. Commercial FEE ? • b) Discrete components vs. ASIC FEE ? • (Application Specific Integrated Circuits) • - Pros vs. Cons - • (price, performance, size, quantity, price/performance • ratio, R&D and production time, maintenance • manpower … but generally, it is more a • project management problem ! ) • - personally, I am trying to avoid generalization ! G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012 Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest

  22. - the dominant pole compensation technique GDC~30,000 Zo~ 66 Ohm NINO, an ultra-fast, low-power, front-end amplifier discriminator for the Time-Of-Flight detector in ALICE experiment F. Anghinolfi et al, ALICE Collab. ANALOGUE CIRCUITS TECHNIQUES, April , 2002; F. ANGHINOLFI ; CERN

  23. “ A Large Ion Collider Experiment, ALICE-TPC -TDR”, ISBN 92-9083-153-3, (1999), CERN

  24. 1. Charge Sensitive Preamplifier ( Low Noise, Fast, Single & Dual Gain ~ 100 dB extended range with ToT ) 2. Programmable Spectroscopic Pulser (as a tool for self-calibrating) 3. Updated frequency compensations to reduce the crosstalk between participants(-from adverse cryostat wiring and up to - electronic crosstalk in the trans. line) C. Chaplin, Modern Times (1936) crosstalk between participants  transfer function issue GSI-2012 8 Clusters (Hole 11.5cm, beam line 11cm) G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012 Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest

  25. Best performance: Majorana dedicated FEE (PTFE~0.4mm; Cu~0.2mm;C~0.6pF; R ~2GΩAmorphous Ge (Mini Systems) ~ 55 eV(FWHM) @ ~ 50 µs (FWHM) BAT17 diode (GERDA) BF862 (2V; 10mA) 1pF; 1 GΩ Test Pulser ? -yes-not & how ? G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012 Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest

  26. Dual Gain Core Structure Ch1 (fast reset)-Pulser @ ~19 MeV Ch2 (linear mode) Ch 1 ~200 mV / MeV C-Ch1 /C-Ch1 INH1 SDHN1 Pole /Zero Adj. Fast Reset (Ch1) Differential Buffer (Ch1) Segments (linear mode) Common Charge Sensitive Loop + Pulser + Wiring Ch 2 ~ 50mV / MeV one MDR 10m cable 36_fold segmented HP-Ge detector + cold jFET C-Ch2 /C-Ch2 INH2 SDHN2 Pole /Zero Adj. Fast Reset (Ch2) Differential Buffer (Ch2) Ch1 ( tr ~ 25.5 ns) Programmable Spectroscopic Pulser Pulser CNTRL Ch2 ( tr ~ 27.0 ns) 2keV -170 MeV @ +/- 12V in two modes & four sub-ranges of operations: a) Amplitude and b) TOT

  27. Segment CSP  Negative Output AGATA CSPs – the versions with large open loop gain ( INFN-Milan – IKP-Cologne) Segment Non-Inverting DC coupled P/Z cancellation Cv R1 R1 Core CSP  Positive Output R1 Core Inverting from Active Reset Cv * (Cv) stability adj. whylarge Ao > 100,000 ?  frequency compensation, slope & crosstalk AC coupled

  28. Fast Reset as tool to implement the “TOT” method Core Active Reset OFF one of the segments Core -recovery from saturation (but base line …) Fast Reset circuitry G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012 Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest

  29. Fast Reset as tool to implement the “TOT” method Core Active Reset – OFF one of the segments Core -recovery from saturation Active Reset – ON Fast Reset circuitry ToT Normal analog spectroscopy one of the segments • very fast recovery from TOT mode of operation • fast comparator LT1719 (+/- 6V) • factory adj. threshold + zero crossing • LV-CMOS (opt) • LVDS by default > 220 MeV @ +/-15V G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012 Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest

  30. Fast Reset as tool to implement the “TOT” method Core Active Reset – OFF one of the segments Core -recovery from saturation Active Reset – ON Fast Reset circuitry ToT Normal analog spectroscopy one of the segments INH-C • very fast recovery from TOT mode of operation • fast comparator LT1719 (+/- 6V) • factory adj. threshold + zero crossing • LV-CMOS (opt) • LVDS by default > 220 MeV @ +/-15V G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012 Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest

  31. see Francesca Zocca PhD Thesis, INFN, Milan A. Pullia at al, Extending the dynamic range of nuclear pulse spectrometers, Rev. Sci. Instr. 79, 036105 (2008) G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012 Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest

  32. Comparison between “reset” mode (ToT) vs. “pulse-height” mode (ADC) A. Pullia at al, Extending the dynamic range of nuclear pulse spectrometers, Rev. Sci. Instr. 79, 036105 (2008)

  33. Due to FADC; G=3 range  ! X-talk ! with CMOS  10 MeV

  34. AGATA Dual-Core LVDS transmission of digital signals: - INH-C1 and INH-C2 (Out) and Pulser Trigger (In) signals AGATA Dual Core crosstalk test measurements Ch2 (analog signal) vs. LVDS-INH-C1 (bellow & above threshold) Core amplitude just below the INH threshold Core amplitude just above the INH threshold Ch1@ INH_Threshold - (~ 4mV) Ch1 @ INH_Threshold + (~ 4mV) Ch2 @ INH_Threshold Vp-Vp(~ 1mV) Ch2@INH_Threshold + (- 1mV) LV_CMOS LV_CMOS INH_Ch1/+/ INH_Ch1/-/ tr ~ 1.65 ns INH_Ch1/+/ tf ~ 2.45 ns INH_Ch1/-/ (1) Core_Ch1, (2) Core_Ch2, (3) INH_Ch1(LVDS/-/, (4) INH_Ch1(LVDS/+/) G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012 Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest

  35. If we have developed a FEE solution with: • Dual gain for the central contact (Core); • ToT for both Core channels and all Segments; • Saturation of the CSP at 170 MeV @ +/-12V … • ( and ~ 220 MeV @ +/- 15V ) • … then why not to perform a direct spectroscopic • measurement up to 170 MeV equivalent gammas ? • … were to find them ? … in cosmic rays! G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012 Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest

  36. To extend the comparison between active “reset” mode (ToT) vs. “pulse-height” mode (ADC) well above 100 MeV measuring directly cosmic rays (i.e. equivalent with inter- action of gamma rays above 100 MeV) • Interaction of muons with matter • Low energy correction: • excitation and ionization ‘density effect’ • High energy corrections: • bremsstrahlung, pair production • and photo-nuclear interaction MUON STOPPING POWER AND RANGE TABLES - 10 MeV|100 TeV D. E. GROOM, N. V. MOKHOV, and S. STRIGANOV David Schneiders, Cosmic radiation analysis by a segmented HPGe detector, IKP-Cologne, Bachelor thesis, 03.11.2011

  37. Two set-up have been used: LeCroy Oscilloscope with only Core signals: Ch1; Ch2, INH-Ch1; INH-Ch2 from Core Diff-to-Single Converter Box 10x DGF-4C-(Rev.E) standard DAQ - complete 36x segments and 4x core signals from Diff-to-Single Converter Boxes (segments & core) David Schneiders, Cosmic radiation analysis by a segmented HPGe detector, IKP-Cologne, Bachelor thesis, 03.11.2011

  38. Experimental results for cosmic ray measurement Calibrated energy sum of all segments vs. both low & high-gain core signals (both in ToT mode of operation) Calibrated energy sum of all segments vs. both low & high-gain core signals (linear & ToT ) Determination of the High Gain Core Inhibit width directly from the trace while the low gain core operates still in linear mode up to ~22 MeV ( deviation ~0.5%) David Schneiders, Cosmic radiation analysis by a segmented HPGe detector, IKP-Cologne, Bachelor thesis, 03.11.2011

  39. Combined spectroscopy up to ~170 MeV Direct measurement of cosmic rays with a HP-Ge AGATA detector, encapsulated and 36 fold segmented • Averaged calibrated segments sum +++ • Averaged calibrated Low gain Core xxx • Scaled pulser calibration (int. & ext.) ---- R.Breier et al., Applied Radiation and Isotopes, 68, 1231-1235, 2010 David Schneiders, Cosmic radiation analysis by a segmented HPGe detector, IKP-Cologne, Bachelor thesis, 03.11.2011

  40. Transfer Function & Crosstalk Transfer function - calculation (Frequency domain, Laplace transf., time domain) - measurement  spectroscopic pulser - applications: - bulk capacities measurement - crosstalk measurements and corrections

  41. In standard way the pulser input signal is injected AC (1pF) in the gate electrode of the jFET δq(t) 1pF 50 Ω The AC coupled Pulser - classical approach ! Detector

  42. δq(t) G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012 Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest

  43. AGATA HP-Ge Detector Front-End Electronics Cold partWarm part AGATA – 3D Dummy detector Cold partWarm part G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012 Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest

  44. AGATA HP-Ge Detector Front-End Electronics Cold partWarm part Cold partWarm part G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012 Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest

  45. Rewritten as a Laplace transform of an exp. decaying function with If τ1 is sufficiently small, the exponential function can be “δ(t)“ and than the transfer function becomes: Simple current dividing rule Miller part Cold resistance equivalent input impedance of the preamplifier

  46. to be able to measure the transfer function, • we need to build and incorporate also a clean pulser with • spectroscopic properties and rectangular pulse form … ! G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012 Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest

  47. Incorporated Programmable Spectroscopic Pulser (PSP) • why is needed?  self-calibration purposes • brief description • Specifications, measurements and application: - Transfer function; - Charge distribution; - Impurities concentration measurements G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012 Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest

  48. The use of PSP for self-calibrating ParameterPotential Use / Applications • Pulse amplitudeEnergy, Calibration, Stability • Pulse FormTransferFunction in time (rise time, fall time, structure)domain, ringing (PSA) • Pulse C/S amplitude ratio  Crosstalk input data (Detector Bulk Capacities)(Detector characterization) • Pulse FormTOT Method (PSA) • Repetition Rate (c.p.s.) Dead Time(Efficiency) (periodical or random distribution) • Time alignment  Correlated time spectra (DAQ) • Segments calibration Low energy and very high energy calibration • Detector characterization  Impurity concentration, passivation (Detector characterization) G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012 Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest

  49. +/- 1ppm • 16 bit +/- 1bit • fast R-R driver CSP return GND • Analog Switches: • -t on / t off , • -Qi, • -dynamic • range (+/- 5V) • Op Amp: • -~ R to R • -bandwidth • Coarse attenuation • (4x 10 dB) (zo~150Ohm) • transmission line • to S_ jFET and • its return GND! G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012 Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest

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