G.Poggi – LEA-LNS – October 2008

G.Poggi – LEA-LNS – October 2008

Recent results of the FAZIA Collaboration Recent results of the FAZIA Collaboration

R&D Phase I of FAZIA consists in optimizing Z and A identification by means of Pulse Shape in Silicon:

• Basic detection module: Si-Si-CsI (non-standard)

• Charge and current preamplifier (PACI)

• Fully digital electronics for Energy, Pulse Shape and Timing has been developed

• Pulse Shape and Silicon material: importance of controlling crystal orientation and doping uniformity

• First prototypes: in-beam tested performances

• Pulse Shape: what are the thresholds (E, Z and A)?

• Pulse Shape + ToF (SPIRAL2 PP + ….)

FAZIA Phase II dedicated to implement results of Phase I:

• Prototype Array (a small scale version of FAZIA)

• New Front End Electronics

R&D Phase I of FAZIA consists in optimizing Z and A identification by means of Pulse Shape in Silicon:

• Basic detection module: Si-Si-CsI (non-standard)

• Charge and current preamplifier (PACI)

• Fully digital electronics for Energy, Pulse Shape and Timing has been developed

• Pulse Shape and Silicon material: importance of controlling crystal orientation and doping uniformity

• First prototypes: in-beam tested performances

• Pulse Shape: what are the thresholds (E, Z and A)?

• Pulse Shape + ToF (SPIRAL2 PP + ….)

FAZIA Phase II dedicated to implement results of Phase I:

• Prototype Array (a small scale version of FAZIA)

• New Front End Electronics

In this talk:

Not discussed, only reminded

Discussed

Briefly addressed and commented

The FAZIA (Four Pi Z and A Identification Array) initiative was formalized in 2006.

Members are from France, Italy, Poland, Spain, Rumania (+Canada, India and US).

The goal of the present Phase I: studying and testing new solutions, checking if possible to make a step forward toward the “ideal” detector array for Dynamics and

Thermodynamics of heavy-ion collisions at Fermi energies and below

http://fazia.in2p3.fr

The FAZIA (Four Pi Z and A Identification Array) initiative was formalized in 2006.

Members are from France, Italy, Poland, Spain, Rumania (+Canada, India and US).

The goal of the present Phase I: studying and testing new solutions, checking if possible to make a step forward toward the “ideal” detector array for Dynamics and

Thermodynamics of heavy-ion collisions at Fermi energies and below

http://fazia.in2p3.fr

The FAZIA InitiativeThe FAZIA Initiative

FAZIA PHASE I: Working Groups

1. Modeling current signals and Pulse Shape Analysis in Silicon (L.Bardelli)

2. Physics cases (G.Verde)

3. Front End Electronics (P.Edelbruck)

4. Acquisition (A.Ordine)

5. Semiconductor Detectors (same as WG1)

6. CsI(Tl) crystals (M.Parlog)

7. Single Chip Telescope (G.P.)

8. Design, Detector, Integration and Calibration (M.Bruno)

9. Web site (O.Lopez)

FAZIA PHASE I: Working Groups

1. Modeling current signals and Pulse Shape Analysis in Silicon (L.Bardelli)




5. Semiconductor Detectors (same as WG1)





CsI(Tl)H.I.

ΔE1 ΔE2

Si Si

?

300μm 500 / 700μm 30-100 mm


B CN

O

Beyond E-E: Z and A Identification with Pulse ShapeBeyond E-E: Z and A Identification with Pulse Shape

Energy vs rise-time of charge signals permits good Z identification of stopped particles (further identification criteria under study)

A threshold exists for Z identification, for small particle penetration (a few tens of μm)

Evidences exist that isotope separation (A identification) is possible above a certain penetration.

Why Pulse Shape in Silicon is possible?

• Stopped particles with the same energy and different Z (and A) show charge/current signals having unlike time evolution because ranges and plasma erosion times differ

• Better identification for reverse-mount Silicon

Why Pulse Shape in Silicon is possible?

• Stopped particles with the same energy and different Z (and A) show charge/current signals having unlike time evolution because ranges and plasma erosion times differ

• Better identification for reverse-mount Silicon

First fully digital implementation of PSA in Silicon: L.Bardelli et al: NP A746 (2004) 272

First fully digital implementation of PSA in Silicon: L.Bardelli et al: NP A746 (2004) 272


“Channeling” and doping non -uniformity in Si for PSA “Channeling” and doping non -uniformity in Si for PSA

nsC

urr

ent

[a.u

]

82Se @ 408 MeV

Elastic scattering on Au

~100 mm2 Silicon


Only very small scale implementation of high-quality PSA are reported in the literature (Mutterer et al IEEE TNS 47 (2000) 756 )

Chimera is a large scale implementation of analogue pulse shape with front-mount detectors



“Channeling” and doping non -uniformity in Si for PSA “Channeling” and doping non -uniformity in Si for PSA

Basing on an older work (G.P. et al. NIM B119 (1996) 375) on channeling effects on stopped h.i., we suspected that crystal orientation (and doping non-uniformity) was originating these instabilities.

Could this also explain overall irreproducibility of PSA quality observed in the past?

Basing on an older work (G.P. et al. NIM B119 (1996) 375) on channeling effects on stopped h.i., we suspected that crystal orientation (and doping non-uniformity) was originating these instabilities.

Could this also explain overall irreproducibility of PSA quality observed in the past?





Early FAZIA tests of our DPSA in Silicon with mono-energetic heavy-ions showed fluctuations in current and charge signal shape (also partly irreproducible)

Early FAZIA tests of our DPSA in Silicon with mono-energetic heavy-ions showed fluctuations in current and charge signal shape (also partly irreproducible)

The key experiment: collimated Silicon detectors mounted on a remote-controlled precision goniometer. Signal behavior as a function of the impinging ion direction with respect to crystal axes.

Both <100> and <111> silicon detectors have been studied

The key experiment: collimated Silicon detectors mounted on a remote-controlled precision goniometer. Signal behavior as a function of the impinging ion direction with respect to crystal axes.

Both <100> and <111> silicon detectors have been studied

nsC

urr

ent

[a.u

]

82Se @ 408 MeV

Elastic scattering on Au


Signal Risetime and “Channeling” in <100> and <111> SiliconSignal Risetime and “Channeling” in <100> and <111> Silicon

Our findings for “Channeled” or “random-entering” stopped ions

“Channeled” ions: strongly fluctuating rise-time due to…

enhanced variations of range and plasma erosion time for directions close to crystal axes, which are basically…




“Channeled”

“Channeled”

ns

80Se @ 408 MeV


Signal Risetime and “Channeling” in <100> and <111> SiliconSignal Risetime and “Channeling” in <100> and <111> Silicon

If detectors subtend ~1° and are mounted in the usual way, most ions may experience abnormal fluctuations, given the large channeling probability (ψ½ = 0.5°-1°)

“Channeling" in Silicon is observed for front and rear injection

If detectors subtend ~1° and are mounted in the usual way, most ions may experience abnormal fluctuations, given the large channeling probability (ψ½ = 0.5°-1°)

“Channeling" in Silicon is observed for front and rear injection

“Channeled”

ns

80Se @ 408 MeV

“Random”

“Random”

ns

80Se @ 408 MeV

Risetime-fluctuations vs gonio-angles

<111> Si Flu

ctu

ati

on

in

cre

as

es

For <111> Silicon: typically 7° off-axis




… absent for random directions




… absent for random directions


Signal Risetime and Channeling in <100> and <111> SiliconSignal Risetime and Channeling in <100> and <111> Silicon

The mandatory recipe for good Pulse Shape

Analysis:

USE PURPOSELY ORIENTED SILICON

DETECTORS for ALWAYS MAINTAINING RANDOM

INCIDENCE

We have ordered indeed special-cut

nTD wafers

The mandatory recipe for good Pulse Shape

Analysis:

USE PURPOSELY ORIENTED SILICON

DETECTORS for ALWAYS MAINTAINING RANDOM

INCIDENCE

We have ordered indeed special-cut

nTD wafers

80Se @ 408 MeV <100> Silicon

Cu

rren

t [a

.u] “Channeled”

ns

“Random”

ns

Irreproducibility: minor geometry variations of the setup change the fraction of channeled ions

Unfortunately this does not explain everything… The Silicon doping uniformity must also be

controlled up to an unprecedented levelThis information is basically not available from

(detector/wafer) manufacturers

L.Bardelli et al: under tedious refereeing procedure on NIMA

L.Bardelli et al: under tedious refereeing procedure on NIMA


Fixed impact point

Various bias voltage

Fixed impact point


Over depletion

Full bias

Slightly under-bias

T_rise

Resistivity measurements (doping uniformity) in SiliconResistivity measurements (doping uniformity) in Silicon

A newly developed procedure to map Silicon resistivity, based on Transient Current Technique, has been developed and systematically applied to our

detectors

A newly developed procedure to map Silicon resistivity, based on Transient Current Technique, has been developed and systematically applied to our

detectors

Reverse-mount Silicon det.

Various applied voltages: from under- to over bias

Narrow UV laser pulse (ns)

RSi detector


Fixed impact point


Fixed impact point


Over depletion

Full bias

Slightly under-bias

T_rise





RSi detector

A newly developed procedure to map Silicon resistivity, based on Transient Current Technique has been systematically applied to our detectors



A typical detector: ~9% non-uniformity with

striations (mm-1 spatial frequency)

Fixed impact point


Fixed impact point


Over depletion

Full bias

Slightly under-bias

T_rise





RSi detector

A non typical, very good detector:

~1% non-uniformity with

undetectable striations



Memento: good resistivity uniformity good uniformity of electric field position-independent signal shape best available PSA


PSA test run with full control of channeling and resistivity

32S + 27Al @ 474 MeV (LNL, December 2007)

PSA test run with full control of channeling and resistivity

32S + 27Al @ 474 MeV (LNL, December 2007)

Si-Si, Si-CsI and “Single Chip Tel” have been used. All Silicons were characterized for uniformity, were un-collimated and have the “FAZIA” dimensions(400mm2)

PACI preamps

A fully digital FEE for charge and current PSA has been developed (Orsay+Florence) for Phase I

Si-Si, Si-CsI and “Single Chip Tel” have been used. All Silicons were characterized for uniformity, were un-collimated and have the “FAZIA” dimensions(400mm2)

PACI preamps

A fully digital FEE for charge and current PSA has been developed (Orsay+Florence) for Phase I

Channeling control for the experiment:

Detectors made of random-cut Silicon were not yet available

All detectors are cut 0° off <111> axis

Channeling--random control obtained by proper 7° detector tilting (simple mechanical adjustment permits to switch from unwanted channeling to desired “random” orientations)

Channeling control for the experiment:

Detectors made of random-cut Silicon were not yet available

All detectors are cut 0° off <111> axis

Channeling--random control obtained by proper 7° detector tilting (simple mechanical adjustment permits to switch from unwanted channeling to desired “random” orientations)

Channeled ions Random entering ions

Quasi-random entering ionsWrong detector mounting causes some residual planar channeling

Wrong detector mounting causes some residual planar channeling


32S + 27Al @ 474 MeV (December 2007)

Channel or not to channel?

32S + 27Al @ 474 MeV (December 2007)


300

μ

500

μ

32S +27Al @ 474 MeV

Pulser

Very uniform 500μm Silicon

Standard mounting, i.e. perpendicular ion incidence is expected to induce channeling

Satisfactory Z identification over the full examined range


Standard mounting, i.e. perpendicular ion incidence is expected to induce channeling


Normally impinging ions

DIGITAL PULSE SHAPE on 500μ Silicon

Full scale: ~1.5 GeV

Be

B

C

N

O

F

NeNa

Are crystal orientation effects really important?


32S +27Al @ 474 MeV

Pulser

300

μ

500

μ


“Channeling” was partly spoiling overall identification

Random: 7° tilt angle

Mass identification clearly shows up!


“Channeling” was partly spoiling overall identification

Random: 7° tilt angle

Mass identification clearly shows up!

Random impinging ions


Full scale: ~1.5 GeV

Be

B

C

N

O

F

NeNa

Yes, they are! “Channeling” was

spoiling the available mass identification

32S + 27Al @ 474 MeV (December 2007)


32S + 27Al @ 474 MeV (December 2007)



32S +27Al @ 474 MeV

500

μ



Full scale: ~ 4 GeV

BeB

CN

OF

NeNa

Mg

AlSi

P

SCl

Ar K

32S + 27Al @ 474 MeV (December 2007)


32S + 27Al @ 474 MeV (December 2007)



Standard mounting, i.e. perpendicular ion incidence


Note the very high energy range


Standard mounting, i.e. perpendicular ion incidence


Note the very high energy range

Unity counts removed


500

μ



Full scale: ~ 4 GeV


32S +27Al @ 474 MeV

BeB

CN

OF

NeNa

Mg

AlSi

P

SCl

Ar K

32S + 27Al @ 474 MeV (December 2007)


32S + 27Al @ 474 MeV (December 2007)



“Channeling” was partly spoiling identification

“Random” mounting


“Channeling” was partly spoiling identification

“Random” mounting


300

μ

500

μ


Digital E-E 300-500μ Silicon (reverse mount)

Full scale E: ~4GeV

Full scale E: ~1.5 GeV

32S + 27Al @ 474 MeV (December 2007)

A two-slide digression: how about “channeling” and the E-E approach?

32S + 27Al @ 474 MeV (December 2007)

A two-slide digression: how about “channeling” and the E-E approach?

Telescope mounted for standard normal incidence

Why so-so resolution?

Is it due to the reverse mount configuration as some claim?

Telescope mounted for standard normal incidence

Why so-so resolution?

Is it due to the reverse mount configuration as some claim?

32S +27Al @ 474 MeV

BeB

C

N

O

F

Ne

Na

LiUnity counts removed


Try a little, proper detector tilting …

32S +27Al @ 474 MeV

300

μ

500

μ


Digital E-E 300-500μ Silicon (reverse mount)

Full scale E: ~4GeV

Full scale E: ~1.5 GeV

Telescope mounted for 7° incidence (Quasi-random configuration)

Telescope mounted for 7° incidence (Quasi-random configuration)

BeB

C

N

O

F

Ne

Na

Li

32S + 27Al @ 474 MeV (December 2007)

Beneficial effects of random incidence for standard E-E identification

32S + 27Al @ 474 MeV (December 2007)

Beneficial effects of random incidence for standard E-E identification

Improper crystal orientation was the

culprit. With “random” orientation the poor resolution is gone



Back to Pulse Shape Analysis

DIGITAL PULSE SHAPE on 500μm and 300μm Silicons with similar field and different doping non-uniformities

300μm: ~ 4 GeV full scale


32S + 27Al @ 474 MeV (December 2007): doping uniformity32S + 27Al @ 474 MeV (December 2007): doping uniformity

Quasi-random, but non-uniform Silicon shows reasonable Z resolution


Quasi-random, very uniform Silicon shows clean Z and partial A resolution


250V on 500μm

1% non-uniformity

BeB

CN

OF

NeNaMg

Al SiPS Cl Ar

K Ca

500

μ

140V on 300μm

9.4% non-uniformity

BeBC

NO FNe

NaMgAl

SiP S

Cl?Ar?

300

μ



140V on 300μm

9.4% non-uniformity

BeBC

NO FNe

NaMgAl

SiP S

Cl?Ar?

140V on 300μm

9.4% non-uniformityC

N

O

F

Ne

NaMg

Al

300

μ50

0 μ





DIGITAL PULSE SHAPE on 500μm and 300μm Silicons with similar field and different doping non-uniformities



250V on 500μm

1% non-uniformity

BeB

CN

OF

NeNaMg

Al SiPS Cl Ar

K Ca

500

μ

C

N

O

F

Ne

NaMg

Al

250V on 500μm

1% non-uniformity G.Poggi – LEA-LNS – October 2008

Simulation: 1.3% non-uniformity, electronic noise and longitudinal straggling

Simulation: perfect uniformity, electronic noise and longitudinal straggling included

Simulation: %5 non uniformity, electronic noise and longitudinal straggling



What are the limits imposed by doping non-uniformity?

The answer may come from simulations, based on calculations by W.Seibt et al (NIM 113 (1973) 317), introducing a local variation of depletion voltage as a function of particle impact point (S.Carboni, Master Thesis, in preparation)

What are the limits imposed by doping non-uniformity?

The answer may come from simulations, based on calculations by W.Seibt et al (NIM 113 (1973) 317), introducing a local variation of depletion voltage as a function of particle impact point (S.Carboni, Master Thesis, in preparation)

Simulation is basically able to reproduce the data: doping non-uniformity must be around 1% if mass resolution is aimed at (data is now only available for A=10-20)

Simulation is basically able to reproduce the data: doping non-uniformity must be around 1% if mass resolution is aimed at (data is now only available for A=10-20)

Experiment: measured 1.3% non-uniformity

BeB

CN

O

Preliminary conclusions:

with uniformity-controlled and “random”-oriented Silicon detectors, Digital PSA developed in FAZIA permits unity charge resolution at least up to Z ~ 30 (probably >50), with energy thresholds of about 3MeV/n for C and 4MeV/n for Ne (about 30-40 μm of Silicon)

DPSA gives mass resolution for Z<15-20 (conclusion also based on short-run results with 58,60Ni) particles, when ranges are <100μm (?) of Silicon

ToF might significantly extend this mass resolution

Preliminary conclusions:

with uniformity-controlled and “random”-oriented Silicon detectors, Digital PSA developed in FAZIA permits unity charge resolution at least up to Z ~ 30 (probably >50), with energy thresholds of about 3MeV/n for C and 4MeV/n for Ne (about 30-40 μm of Silicon)

DPSA gives mass resolution for Z<15-20 (conclusion also based on short-run results with 58,60Ni) particles, when ranges are <100μm (?) of Silicon

ToF might significantly extend this mass resolution

FAZIA Phase I: Digital Pulse Shape on SiliconFAZIA Phase I: Digital Pulse Shape on Silicon

58Ni

60Ni

These preliminary results look promising…


Best algorithms for DPSA are under study within FAZIA WG1:


FAZIA Phase I: next stepsFAZIA Phase I: next steps

3rd vs 2nd moment of current signals

S.Barlini et al: in preparation


E vs (E and Imax) linear combination

Improved Z and A discrimination

E vs (E and Imax) linear combination

Improved Z and A discrimination

Be

BC

N

O F

Li


Adding ToF to current or charge risetime for extending mass resolution of low energy stopped particles

Trying to get ToF even with non-optimal time structure of the pulsed beam (supported by Spiral2 PP)

Addressing Digital Pulse Shape for Silicon strip and Z = 1,2 ions (supported by Spiral2 PP)

Future experiments: LNS and GANIL…


Adding ToF to current or charge risetime for extending mass resolution of low energy stopped particles

Trying to get ToF even with non-optimal time structure of the pulsed beam (supported by Spiral2 PP)

Addressing Digital Pulse Shape for Silicon strip and Z = 1,2 ions (supported by Spiral2 PP)

Future experiments: LNS and GANIL…

FAZIA Phase I: next stepsFAZIA Phase I: next steps

Y axis: measured energy

X axis: measured rise-time + simulated ToF over 1.1m and 0.5 ns FWHM (smoothly merged)

Y axis: measured energy

X axis: measured rise-time + simulated ToF over 1.1m and 0.5 ns FWHM (smoothly merged)

Exp+Sim


~104 telescopes

Phase II (from 2008 till 2012):

• Prototype Array (20-30 modules) to couple with existing arrays and do Physics out of it

• Implement the solutions devised and tested on Phase I

• adopt electronic and mechanical solutions as close as possible to the final 4π configuration (e.g. neutron detection feasibility and transportability)

• Phase III (from 2012 on):

• Build a Demonstrator, covering a significant fraction of 4π, e.g C2+C1

Phase II (from 2008 till 2012):

• Prototype Array (20-30 modules) to couple with existing arrays and do Physics out of it

• Implement the solutions devised and tested on Phase I

• adopt electronic and mechanical solutions as close as possible to the final 4π configuration (e.g. neutron detection feasibility and transportability)

• Phase III (from 2012 on):

• Build a Demonstrator, covering a significant fraction of 4π, e.g C2+C1

FAZIA R&D Phase II (and Phase III)FAZIA R&D Phase II (and Phase III)

A possible final FAZIA Array (JM Gautier-LPC)

x 8

C1C2C3

C4


FEE structure under vacuum to simplify connections (the very issue under study: power removal)

Bidirectional fast (at least 2.2 Gb/s) fiber optics guarantees synchronous trigger info transmission and transfer of samples (data).

The last level provides trigger construction / validation / event labeling + sample dispatching to DAQ

Fast FPGA-based elaboration and protocol management

FEE structure under vacuum to simplify connections (the very issue under study: power removal)

Bidirectional fast (at least 2.2 Gb/s) fiber optics guarantees synchronous trigger info transmission and transfer of samples (data).

The last level provides trigger construction / validation / event labeling + sample dispatching to DAQ

Fast FPGA-based elaboration and protocol management

FAZIA R&D Phase II: the FEEFAZIA R&D Phase II: the FEE

..640....16.. ..16.. ..16..

First Level FEE Unit



Vacuum

Air

Trigger and data collector + dispatcher

Trigger info and samples

2.2 Gb/s

Trigger validation and slow control

2.2 Gb/s

Ethernet

DAQTrigger Box

Trigger info

Trigger validation and event labeling..64.. Samples

Trigger decision (400 ns)

Trigger decision (400 ns)

Data transmission to PC farm

Data transmission to PC farm

Trigger/samples separation and trigger elaboration

Trigger/samples separation and trigger elaboration

Fast and slow Energy shaping

Local digital trigger generation (100 ns)+ second level decision (over in 2-3 μs) + data sending (asynchronous)

Fast and slow Energy shaping

Local digital trigger generation (100 ns)+ second level decision (over in 2-3 μs) + data sending (asynchronous)


The FAZIA organizationThe FAZIA organization

FAZIA Project Management Board: B.Borderie, R. Borcea, R.Bougault, A.Chbihi, F.Gramegna, T.Kozik, I.Martel Bravo, E.Rosato, G.P. and R.Roy

Sc. Coordinators: G.P. and R.Bougault

Tech. Coordinator: P.Edelbruck

FAZIA Project Management Board: B.Borderie, R. Borcea, R.Bougault, A.Chbihi, F.Gramegna, T.Kozik, I.Martel Bravo, E.Rosato, G.P. and R.Roy

Sc. Coordinators: G.P. and R.Bougault

Tech. Coordinator: P.Edelbruck

FAZIA Working Groups

1. Modeling current signals and Pulse Shape Analysis (L.Bardelli)




5. Semiconductor Det. (with WG1)





FAZIA Working Groups

1. Modeling current signals and Pulse Shape Analysis (L.Bardelli)




5. Semiconductor Det. (with WG1)





A dedicated Discussion Group is studying the Physics requirements for the Trigger (M.F.Rivet and A.Olmi) to implement with our electronic engineers


We are still shocked and deeply sad: our friend and precious colleague Jean

Marc Gautier died few days ago

We are still shocked and deeply sad: our friend and precious colleague Jean

Marc Gautier died few days ago

Documents

G.Poggi – LEA-LNS – October 2008