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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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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


  • 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


A typical structure of a segmented tapered and encapsulated hp ge detector
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


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


[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


Detector signal collection

+

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)?


Detector signal collection1

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


Charge sensitive preamplifier
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)


Pole zero cancellation technique
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


Pole zero cancellation technique1
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


Pole zero cancellation technique2
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


  • 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


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


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


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


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


  • 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


  • 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


  • 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


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


  • 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


- 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



1. Charge Sensitive Preamplifier 92-9083-153-3, (1999), CERN

( 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


Best performance: 92-9083-153-3, (1999), CERNMajorana 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


Dual Gain Core Structure 92-9083-153-3, (1999), CERN

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


Segment CSP 92-9083-153-3, (1999), CERN 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


Fast Reset as tool to implement the “TOT” method 92-9083-153-3, (1999), CERN

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


Fast Reset as tool to implement the “TOT” method 92-9083-153-3, (1999), CERN

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


Fast Reset as tool to implement the “TOT” method 92-9083-153-3, (1999), CERN

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


see 92-9083-153-3, (1999), CERNFrancesca 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


Comparison between “reset” mode 92-9083-153-3, (1999), CERN(ToT) vs. “pulse-height” mode (ADC)

A. Pullia at al, Extending the dynamic range of nuclear pulse spectrometers,

Rev. Sci. Instr. 79, 036105 (2008)


Due 92-9083-153-3, (1999), CERNto

FADC; G=3

range  !

X-talk !

with CMOS

 10 MeV


AGATA Dual-Core 92-9083-153-3, (1999), CERNLVDS 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

[email protected] INH_Threshold - (~ 4mV)

Ch1 @ INH_Threshold + (~ 4mV)

Ch2 @ INH_Threshold

Vp-Vp(~ 1mV)

[email protected]_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


  • If we have developed a FEE solution with: 92-9083-153-3, (1999), CERN

  • 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


To 92-9083-153-3, (1999), CERNextend 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


Two set-up have been used: 92-9083-153-3, (1999), CERN

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


Experimental results for cosmic ray measurement 92-9083-153-3, (1999), CERN

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


Combined 92-9083-153-3, (1999), CERNspectroscopy

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


Transfer Function 92-9083-153-3, (1999), CERN& Crosstalk

Transfer function

- calculation (Frequency domain, Laplace transf., time domain)

- measurement  spectroscopic pulser

- applications:

- bulk capacities measurement

- crosstalk measurements and

corrections


In standard way the 92-9083-153-3, (1999), CERNpulser 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


δ 92-9083-153-3, (1999), CERNq(t)

G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012

Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest


AGATA 92-9083-153-3, (1999), CERN

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


AGATA 92-9083-153-3, (1999), CERN

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


Rewritten as a Laplace 92-9083-153-3, (1999), CERN

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


!

G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012

Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest


Incorporated 92-9083-153-3, (1999), CERNProgrammable 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


The 92-9083-153-3, (1999), CERNuse 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


  • +/- 1ppm 92-9083-153-3, (1999), CERN

  • 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


AGATA 92-9083-153-3, (1999), CERN

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


Pulser ratio core segments
Pulser Ratio Core 92-9083-153-3, (1999), CERN/ Segments

Uncorrected for individual segment gain

Corrected for each individual segment gain


Core and segment crosstalk

Agata 92-9083-153-3, (1999), CERN

measured capacities:

C0-X6 = 0.98 pF

C0-X5 = 1.16 pF

C0-X4 = 1.19 pF

C0-X3 = 0.980 pF

C0-X2 = 0.666 pF

Segment normalization

C0-X1 = 0.943 pF

Core normalization

Observed shift in segments

Core and Segment crosstalk


3D Space charge reconstruction in highly segmented 92-9083-153-3, (1999), CERN

HP-Ge detectors through CV measurements, using PSP

  • The reconstruction of the three dimensional space charge distribution

  • inside highly segmented large volume HP-Ge Detector from

  • C-V measurement was investigated

  • A computer program was developed to understand the impact of impurity

  • concentrations on the resulting capacities between core contact and

  • outer contact for HP-Ge detectors biased at different high voltages

  • The code is intended as a tool for the reconstruction of the doping

  • profile within irregularly shaped detector crystals.

  • The results are validated by comparison with the exact solution of a

  • true coaxial detector.

  • Existing methods for space charge parameter extraction are shortly revised.

  • The space charge reconstruction under cylindrical symmetry is derived.

G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012

Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest


Influence of the space 92-9083-153-3, (1999), CERN

charge on the core

signal rise time

(in the coaxial part of

the AGATA detector )

The example indicates the need for

characterization of each individual

detector, including detailed investigation

of space charge distribution and the

exact geometry of the sensitive material


  • simple planar capacitor 92-9083-153-3, (1999), CERN

  • from charge neutrality condition

  • of the device ( N(d)being the

  • remaining net charge at the boundary

  • of the depletion region)to the variations

  • in capacity with the bias voltage and

  • as function of the changing bias

  • voltage a scan through the depletion

  • depth of the sample is obtained only

  • the relationship between measured

  • bulk capacity and applied bias voltage

  • is sufficient to reconstruct the doping

  • profile

  • N.B. - one dimensional reconstruction 

  • planar approximation, where the space

  • charge depending only on “d”

N(d) = [ND -NA ]

where ND ; NA donator, acceptor

concentration levels of the crystal

  • The novel approach is a full 3D

  • reconstruction of the impurity

  • profile throughout the bulk of

  • the HP-Ge crystal.

  • The technique should be applicable

  • for any detector geometry, not only

  • for planar detectors.

G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012

Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest


Electrical model of 36-fold segmented detector 92-9083-153-3, (1999), CERN

Current [pA]

Core

electrode

Bias [V]

G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012

Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest


Impurities concentration of last four rings of AGATA detector S002

B. Birkenbach at al, Determination of space charge distributions in highly segmented

large volume HP-Ge detectors from capacitance-voltage measurements

Nucl. Instr. Meth. A 640 (2011) 176-184


[10 detector S00210 /cm 3 ]

Crystal Height [mm]

Pulser peak position for different voltages of det. C006


Energy vs. Applied Voltage detector S002

Detector Capacity vs. Applied Voltage

  • Variation of the Am (59.5keV) peak position with detector bias voltage (the error

  • bars indicate the FWHM of the energy peak – they do not represent an uncertainty)

  • The core energy position is strongly varying with bias voltage, while segments

  • are nearly unaffected. The FWHM width is drastically growing due to the

  • increased detector capacity

G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012

Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest


Crosstalk and signal induction in segmented detectors detector S002

  • Segmented detector show mutual capacitive coupling of the: - segments & -core 

  • crosstalk and worsening the energy resolution

  • The crosstalk has to be measured experimentally and to be corrected while due

  • to crosstalk effect the segment sum peak energy value (“add-back”) is reduced

  • The radiation leave a trail of ionization in the detector and the movement of these charges in an electric field induces signals on the detector electrodes.

    • In the case of a detector with ideal segmentation and ideal distributed capacitors one can calculate the signal with an electrostatic approximation using the so called “Ramo theorem” (HP-Ge Det.; MWPC; DSSSD).

    • In the case of under-depleted DSSD; MRPC-detectors the time dependence

    • of the signal is not only given by the movement of the charges but also

    • by the time-dependent reaction of the detector materials. Using quasi-static

    • approximation of Maxwell’s equations –W. Rieglerdeveloped an extended formalism to allows calculation of induced signals for a larger number of detectors with general materials by time dependent weighting fields


without X-talk

with X-talk

G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012

Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest


The segment sum energy for detector S002

Eγ= 1332.5 keV plotted

for different segment

multiplicities (‘fold’ –

number of hit segments)

Energy shift and ‘resolution’ vs. segment ‘fold’


The data points in this figure show peak energy shifts of the 1332.5 keV line

of 60Co as a function of all possible twofold segment combinations.

A refined inspection of the peak position of the twofold events reveals a

regular pattern as a function of pair wise segment combinations


Miniball the 1332.5 (HeKo) PSC 823 PSC-2008 AGATA like Miniball

(Eurysis /Ortec propr. prod.) (differential out.) 2011-2012

Either

BF862 or

IF1320

INH

SHDN

  • Technical Specifications

  • - conversion factor ~ 200 mV/MeV (PSC-2008 opt. 100 mV/MeV)

  • - open loop gain Ao ~ 20,000 The new series 2008 & 2012

  • - single ended - reconfigurable as Inv. / Non Inv.); - Ao ~ 100,000

  • - adjustments: - Idrain; - P/Z adj. ; - Offset adj. ; Bandwidth - differential outputs

  • - adjustments: - Idrain; - P/Z adj. ; - Offset adj. ; Bandwidth - INH-C & SDHN

  • - power supply: +/- 12V (i.e. ToT mode of operation)

  • -rise time ~ 25 ns / 39 pF det. cap. (terminated)


Advanced solution for FEE: the 1332.5

- to extend the dynamic range and counting rate with a

combined dual gain and dual ToT method  100dB;

- transfer function tools ( from dummy to freq. comp.);

- programmable spectroscopic pulser;

- applications as:

- impurities concentration

- up to ~180 MeV equiv. gamma range

- crosstalk corrections


AGATA the 1332.5

Dual Gain Core

Final Specs.

  • Summary active reset:

  • - active reset @ 2nd stage

  • - active reset @ 1st stage

  • with advantages vs. disadv.

G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012

Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest


Miniball charge sensitive preamplifier specifications
MINIBALL the 1332.5 Charge Sensitive Preamplifier Specifications

  • By design optimized

  • Transfer Function

  • (no over/under-shoots)

  • Crosstalk requirements

  • < 10-3core-segment

G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012

Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest


A. Wendt et al – the 1332.5 Der LYCCA-Demonstrator, HK 36.60, DPG, Bonn, 2010

G. Pascovici,Institute of Nuclear Physics, Univ. of Cologne


LYCCA-0 the 1332.5

Set-up for DSSSD + CsI

TASISpec (TASCA)

A new detector Set-up for

Superheavy Element Spectroscopy


G. Pascovici the 1332.5 , Carpathian Summer School of Physics, Sinaia 2012

Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest


~1.25 sq.cm the 1332.5

G. Pascovici , Carpathian Summer School of Physics, Sinaia 2012

Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest


G. Pascovici the 1332.5 , Carpathian Summer School of Physics, Sinaia 2012

Institute of Nuclear Physics, Univ. of Cologne and NIPNE-HH, Bucharest


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