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FAZIA Collaboration : recent advances and perspectives. R&D Phase I of FAZIA and 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)

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slide1

FAZIA Collaboration: recent advances and perspectives

  • R&D Phase I of FAZIA and 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 channeling and doping uniformity
    • First prototypes tested in-beam
    • Pulse Shape: what are the thresholds (E, Z and A)?
    • Pulse Shape + ToF (SPIRAL2 PP + ….)
    • Pulse Shape for low energy hydrogen and helium isotopes
  • 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

G.Poggi – EURORIB08 – June 2008

slide2

ΔE1

ΔE2

Si

Si

CsI(Tl)

H.I.

?

300μm

500 / 700μm

30-100 mm

The FAZIA Initiative

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

  • FAZIA PHASE I: Working Groups
  • Modeling current signals and Pulse Shape Analysis in Silicon (L.Bardelli)
  • Physics cases (G.Verde)
  • Front End Electronics (P.Edelbruck)
  • Acquisition (A.Ordine)
  • CsI(Tl) crystals (M.Parlog)
  • Single Chip Telescope (G.P.)
  • Design, Detector, Integration and Calibration (M.Bruno)
  • Web site (O.Lopez)

G.Poggi – EURORIB08 – June 2008

slide3

O

N

C

B

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

  • Why Pulse Shape inSilicon 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

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.

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

G.Poggi – EURORIB08 – June 2008

slide4

82Se @ 408 MeV

Elastic scattering on Au

~100 mm2 Silicon

Current [a.u]

ns

Channeling and doping non -uniformity in Si for PSA

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

G.Poggi – EURORIB08 – June 2008

slide5

82Se @ 408 MeV

Elastic scattering on Au

Current [a.u]

ns

Channeling and doping non -uniformity in Si for PSA

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

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

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

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

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

G.Poggi – EURORIB08 – June 2008

slide6

“Channeled”

80Se @ 408 MeV

“Channeled”

ns

Signal 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 channels, which are basically…

G.Poggi – EURORIB08 – June 2008

slide7

“Random”

80Se @ 408 MeV

80Se @ 408 MeV

“Channeled”

“Random”

Risetime-fluctuations vs gonio-angles

ns

ns

Fluctuation increases

<111> Si

Signal 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 channels, which are basically…

… absent for random directions

L.Bardelli et al; submitted to NIMA

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

If detectors subtend ~1° and are mounted in theusual 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

G.Poggi – EURORIB08 – June 2008

slide8

80Se @ 408 MeV <100> Silicon

“Channeled”

“Random”

Current [a.u]

ns

ns

Signal 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

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 level

This information is basically not available from (detector/wafer)manufacturers

L.Bardelli et al: submitted to NIMA

G.Poggi – EURORIB08 – June 2008

slide9

R

Fixed impact point

Various bias voltage

Over depletion

Full bias

Slightly under-bias

T_rise

Resistivity measurements (doping uniformity) in Silicon

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

Narrow UV laser pulse (ns)

Si detector

Reverse-mount Silicon det.

Various applied voltages: from under- to over bias

G.Poggi – EURORIB08 – June 2008

slide10

R

Fixed impact point

Various bias voltage

Over depletion

Full bias

Slightly under-bias

T_rise

Resistivity measurements (doping uniformity) in Silicon

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-uniformitywith striations (mm-1 spatial frequency)

Narrow UV laser pulse (ns)

Si detector

Reverse-mount Silicon det.

Various applied voltages: from under- to over bias

G.Poggi – EURORIB08 – June 2008

slide11

R

Fixed impact point

Various bias voltage

Over depletion

Full bias

Slightly under-bias

T_rise

Resistivity measurements (doping uniformity) in Silicon

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

Narrow UV laser pulse (ns)

Si detector

A non typical, very good detector: ~1% non-uniformitywith undetectable striations

Memento: good resistivity uniformity  good uniformity of electric field  position independence of timing

Reverse-mount Silicon det.

Various applied voltages: from under- to over bias

G.Poggi – EURORIB08 – June 2008

slide12

Quasi-random entering ions

Channeled ions

Random entering ions

Wrong detector mounting causes some residual planar channeling

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

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)

G.Poggi – EURORIB08 – June 2008

slide13

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

Channelor not to channel?

DIGITAL PULSE SHAPE on 500μ Silicon

Full scale: ~1.5 GeV

32S +27Al @ 474 MeV

Normally impingingions

Are channeling effects really important?

F

Pulser

Ne

O

Na

300 μ

500 μ

N

Very uniform500μm Silicon

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

Satisfactory Z identification over the full examined range

C

B

Be

G.Poggi – EURORIB08 – June 2008

slide14

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

Channel ornot to channel?

DIGITAL PULSE SHAPE on 500μ Silicon

Full scale: ~1.5 GeV

32S +27Al @ 474 MeV

Yes, they are! Channeling was spoiling mass identification

Randomimpingingions

F

Pulser

Ne

O

Na

300 μ

500 μ

N

Very uniform500μm Silicon

Channeling was partly spoiling overall identification

Random:7° tilt angle

Mass identification clearly shows up!

C

B

Be

G.Poggi – EURORIB08 – June 2008

slide15

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

Channelor not to channel?

DIGITAL PULSE SHAPE on 500μ Silicon

Full scale: ~ 4 GeV

32S +27Al @ 474 MeV

S

Normallyimpingingions

Cl

P

Ar

Si

K

Al

Mg

500 μ

Na

Ne

F

Very uniform500μm Silicon

Standard mounting, i.e. perpendicular ion incidence

Satisfactory Z identification over the full examined range

Note the very high energy range

O

N

C

B

Be

Unity counts removed

G.Poggi – EURORIB08 – June 2008

slide16

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

Channel or not to channel?

DIGITAL PULSE SHAPE on 500μ Silicon

Full scale: ~ 4 GeV

32S +27Al @ 474 MeV

S

Random impingingions

Cl

P

Ar

Si

K

Al

Mg

500 μ

Na

Ne

F

Very uniform500μm Silicon

Channeling was partly spoiling identification

“Random”mounting

O

N

C

B

Be

Unity counts removed

G.Poggi – EURORIB08 – June 2008

slide17

140V on 300μm

9.4% non-uniformity

S

P

Cl?

Si

Ar?

Al

Mg

Na

Ne

F

O

N

C

300 μ

B

Be

250V on 500μm

1% non-uniformity

S

Cl

Ar

P

Si

K

Al

Ca

Mg

Na

Ne

F

O

N

C

500 μ

B

Be

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

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

300μm: ~ 4 GeV full scale

500μm: ~ 4 GeV full scale

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

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

G.Poggi – EURORIB08 – June 2008

slide18

Al

140V on 300μm

9.4% non-uniformity

Mg

Na

S

P

Ne

Cl?

Si

Ar?

Al

F

Mg

Na

O

Ne

F

O

N

N

C

B

Be

140V on 300μm

9.4% non-uniformity

C

Al

Mg

250V on 500μm

1% non-uniformity

Na

Ne

S

Cl

Ar

P

Si

K

F

Al

Ca

Mg

Na

O

Ne

F

O

N

N

C

500 μ

B

C

Be

250V on 500μm

1% non-uniformity

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

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

300μm: ~ 4 GeV full scale

500μm: ~ 4 GeV full scale

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

300 μ

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

500 μ

G.Poggi – EURORIB08 – June 2008

slide19

60Ni

58Ni

FAZIA Phase I: Digital Pulse Shape on Silicon

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(also based on short-run results with 58,60Ni) particles, with ranges > 100μm (?) of Silicon

ToF might significantly extend this mass resolution

Frankly, we are not unhappy about these preliminary results…

G.Poggi – EURORIB08 – June 2008

slide20

3rd vs 2nd moment of current signals

Exp+Sim

Y axis: measured energy

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

FAZIA Phase I: next steps

Best algorithms for DPSA are under study within FAZIA WG1 (S.Barlini et al: in preparation)

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: LNL, LNS, GANIL…

G.Poggi – EURORIB08 – June 2008

slide21

~104 telescopes

x 8

FAZIA R&D Phase II (and Phase III)

  • 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

C2

C1

C3

C4

A possible final FAZIA Array (JM Gautier-LPC)

G.Poggi – EURORIB08 – June 2008

slide22

Data transmission to PC farm

Trigger decision (400 ns)

Trigger validation and event labeling

Trigger Box

DAQ

Ethernet

Trigger info

..64..

Samples

Trigger and data collector + dispatcher

Trigger/samples separation and trigger elaboration

Trigger info and samples 2.2 Gb/s

Trigger validation and slow control 2.2 Gb/s

Air

Vacuum

Fast and slow Energy shaping

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

First Level FEE Unit

First Level FEE Unit

First Level FEE Unit

..16..

..16..

..16..

..640..

FAZIA R&D Phase II: the FEE

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

Bidirectional fast (2.2 Gb/s) fiber optics guaranteessynchronous trigger infotransmission 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

G.Poggi – EURORIB08 – June 2008

slide23

The FAZIA organization

  • FAZIA Working Groups
  • Modeling current signals and Pulse Shape Analysis (L.Bardelli)
  • Physics cases (G.Verde)
  • Front End Electronics (P.Edelbruck)
  • Acquisition (A.Ordine)
  • CsI(Tl) crystals (M.Parlog)
  • Single Chip Telescope (G.P.)
  • Design, Detector, Integration and Calibration (M.Bruno)
  • Web site (O.Lopez)

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

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

Two more slides on “synergies”

G.Poggi – EURORIB08 – June 2008

slide24

Elastic scattering in

93Nb+116Sn @ 30 MeV/n

E

E

Synergies in instrumentation

Questions fitting very well with our Topic

Is channeling an issue only for PSA-based identification?

How about channeling and more standard identification approaches?

Significant effects are expected in E-E: channeling may change E, as many of us have seen when punching-through elastic scattering is measured

This effect is less clearly appreciated in other cases, but still present

G.Poggi – EURORIB08 – June 2008

slide25

300 μ

500 μ

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

Digital E-E 300-500μ Silicon (reverse field)

Full scale E: ~4GeV

Full scale E: ~1.5 GeV

32S +27Al @ 474 MeV

Try a little, proper detector tilting …

Na

Ne

Normallyimpinging ions

F

O

N

C

B

Telescope mountedfor standard normal incidence

Why so-so resolution?

Never happened to you?

Be

Li

Unity counts removed

G.Poggi – EURORIB08 – June 2008

slide26

300 μ

500 μ

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

Beneficial effects of random incidence for standard E-E identification

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

Full scale E: ~4GeV

Full scale E: ~1.5 GeV

32S +27Al @ 474 MeV

… say channeling “goodbye”

Na

Ne

Randomimpinging ions

F

We believe that one should keep this result in mind for any future E(Si)-Eimplementation. Do not overlook the old recommendation of 7° off-axis cutand double check what you buy.

Thanks to the audience

O

N

C

B

Telescope mounted for 7° incidence(Quasi-randomconfiguration)

Be

Li

Unity counts removed

G.Poggi – EURORIB08 – June 2008