LP

GD

/Dit

an

et

WS

11

/20

11

J.

Pa

nc

in

Low pressure gas detectors

6th Ditanet Workshop on Particle Detection Technics

Short review on low pressure gas detectionExamples of detectorsCurrent R&D on Secondary Electrons Detectors

LP

GD

/Dit

an

et

WS

11

/20

11

J.

Pa

nc

in

History

Low-pressure drift chambers for heavily ionizing particles  Original Research ArticleNuclear Instruments and Methods, Volume 119, July-August 1974, Pages 7-8A. Breskin, G. Charpak, F. Sauli (methylal 300 mbar)    2 A low pressure multiwire proportional chamber as a position sensitive detector of heavy ions: Construction and detection properties  Original Research ArticleNuclear Instruments and Methods, Volume 177, Issues 2-3, 15 November 1980, Pages 427-431J. Stähler, G. Presser (iC4H10 10 mbar) 3 Low-pressure drift chamber with a built-in scintillator  Original Research ArticleNuclear Instruments and Methods, Volume 178, Issue 1, 1 December 1980, Pages 71-75R. Janik, L. Mouc3 ka, V.D. Peshekhonov, B. Sitar (iC4H10 50 torr)    4 Application of a low pressure proportional chamber in ion X-ray coincidence measurements  Original Research ArticleNuclear Instruments and Methods, Volume 176, Issues 1-2, 1 October 1980, Pages 79-82J. Stähler, G. Presser (iC4H10 10 mbar)

5 A low pressure proportional chamber with a high space resolution  Original Research ArticleNuclear Instruments and Methods, Volume 145, Issue 3, 15 September 1977, Pages 437-440V.M. Golovatyuk, A.B. Ivanov, V.A. Nikitin, V.D. Peshekhonov, Yu.V. Zanevsky (methylal 300 mbar)  6 Low pressure multiwire proportional chambers with high time resolution for strongly ionizing particles  Original Research ArticleNuclear Instruments and Methods, Volume 94, Issue 1, 15 June 1971, Pages 27-28F. Binon, V.V. Bobyr, P. Duteil, M. Gouanere, L. Hugon, M. Spighel, J.P. Stroot (iC4H10 50 mbar)

7 Properties of low-pressure drift chambers  Original Research ArticleNuclear Instruments and Methods, Volume 134, Issue 1, 1 April 1976, Pages 35-46A. Breskin, N. Trautner (methylal 10 torr)

8 Properties of different counting gases for a low pressure multiwire proportional chamber  Original Research ArticleNuclear Instruments and Methods, Volume 164, Issue 2, 15 August 1979, Pages 305-310J. Stähler, G. Hemmer, G. Presser (iC4H10 10 mbar)

   

LP

GD

/Dit

an

et

WS

11

/20

11

J.

Pa

nc

in

Detector types

Progress in low-pressure gaseous detectors, A. Breskin et al., NIM196(1982): heavy and light ion detection

Low Pressure detectors: Few materials in beam (few angular or energy straggling for

heavy low nuclei) and operation in vaccum low pressure gas detector

Use of pure iC4H10 for its low ionisation energy (about 100 % efficiency needed) and its high quenching power (very low pressure of several mbar)

Mean free path of electrons much higher : high electron drift speed, early avalanche and good timing resolution

Important gain (E/P…) even in low field region : natural spread of the avalanche, good spatial resolution with low granularity, low threshold applications

Low drift gap and fast ion collection for high rate capabilities

LP

GD

/Dit

an

et

WS

11

/20

11

J.

Pa

nc

in

Signal at low pressure (…vs NTP) No much differences in the ionization process (apart for

delta electrons…) Amplification process much easier at low pressure:

+V0

Signal

CathodeAnode wire

IsobutaneCharged particle

+-

Ex Ei- Minimum field Ec for avalanche multiplication

≈ 40 V/cm/torr

d= 3 mmVc≈10 kV at 1bar

- Increase E: wire chamber (α 1/r)- Decrease gaps: MPGD (micromegas, GEMs, MSGC)- Decrease Pressure !!

LP

GD

/Dit

an

et

WS

11

/20

11

J.

Pa

nc

in

Signal at low pressure (…vs NTP)

UV

Gas mixture at NTP but pure at low pressure Polyatomic gases (several vibration and rotation

modes: non radiative mode) Absorbe the radiated photons Limit the breakdown (at low pressure!!!) Typical quenchers: i-C4H10 , CF4...CO2, CH4

Avalanche appears earlier at low pressure

LP

GD

/Dit

an

et

WS

11

/20

11

J.

Pa

nc

in

Electronical cross sections

- Non radiative modes- Ionization energies- Ionization cross sections

LP

GD

/Dit

an

et

WS

11

/20

11

J.

Pa

nc

in

Gain and Townsend coef. :

Calculation at low pressure

Yu. I. Davydov, IEEE TRANSACTIONS ON NUCLEAR SCIENCE, 53-5, (2006)

)exp(E

BPAP

Rose and korff approx: A=27 cm-1 Torr-1 and B=392 V cm-1 Torr-1 (183 to 438 V cm-1 Torr-

1)

If e<i

α=1/ If e>i

Magboltz simulation for electron drift speed and diffusion (not the gain…)

Difficult to get some good simulations at low pressure : ≈50 m at 10 mbar α=f(dE) and electron not in equilibrum with electric field at VLP (PPAC vs WC)

Þ Laboratory test mandatory to get the real performances

M. Nakhostin et al, Nucl. Instr. And Meth., 572, (2007)

assuming constant mean free path =1/(n) Ei=350-520 V/cm/Torr

LP

GD

/Dit

an

et

WS

11

/20

11

J.

Pa

nc

in

Spatial resolution…

80 mbar

iC4H10

8 mbar

iC4H10

LP

GD

/Dit

an

et

WS

11

/20

11

J.

Pa

nc

in

High ion drift speed

1.6 / 0.128 =12.5…

Mobility of iC4H10 ion in itself: w=0.61 cm2V-1s-1

v= wEP0/P v ≈ 200*wE at 5 mbar which gives v ≈ 0.2 cm/s at 2 kV/cm

1.6 / 0.256 =6.25…

high couting rate capabilities

v≈0.21 cm/s

LP

GD

/Dit

an

et

WS

11

/20

11

J.

Pa

nc

in

Detectors used at low pressure(in nuclear physics…)

Tracking (X,Y,t) with Wire Chambers Energy loss (E) measurements with

ionization chambers: no amplification process

Tracking (X,Y) with Drift Chambers (with very good spatial resolution)

…

LP

GD

/Dit

an

et

WS

11

/20

11

J.

Pa

nc

in

CATS: Beam Tracking Detectors (E>10 A.MeV)

Constant field zone: PPAC, position signal on the strips

High gradient field zone: MWPC, time signal on the wires

t<400 ps, s<0.5 mm, <1mrad Counting rate 105 pps/cm2

Energy threshold ≈ 1 keV Material in beam 550 g/cm2

11C

11C

ProtonEp

Θp

E*

x1,y1

x2,y2

x

c

S. Ottini-Hustache, NIMA 431 (1999).

LP

GD

/Dit

an

et

WS

11

/20

11

J.

Pa

nc

in

Detectors used on VAMOSII Spectrometer

7 m

MW target

Big size MW

2 drift chambers

3 Ionization Chambers

1 wall of 40 S

it X1,

Y1

X2,

Y2

E E1 m

A, Z, Q and v to measure for each nuclei entering spectrometer- energy E=1/2 Av2, with Si detectors- Energy loss ΔE≈AZ2/E for Z, with Si detectors and ICs- Magnetic rigidity Bρ= Av/Q with the spectrometer and the DCs- Velocity v by TOF with the MW

Dedicated to energy below 5 A.MeV : use of low pressure to minimize material in beam for all detectors

M. Rejmund et al., Performance of the improved larger acceptance spectrometer: VAMOS++, Nucl. Inst. And Meth. A, 646 (2011), p 184-191.

LP

GD

/Dit

an

et

WS

11

/20

11

J.

Pa

nc

in

Small Multi-Wire target

• Active area 60x60mm2

• 200 g/cm2 or 120 g/cm2

• Time resolution (300ps)• X, Y resolution (0.5 mm)• Inverse polarisation for ion gating• Counting rate 105 pps/cm2

• Energy thereshold ≈30 keV

2x2.4mm

LP

GD

/Dit

an

et

WS

11

/20

11

J.

Pa

nc

in

Big size MWPPAC: alternative to SED (1 m)

- Used on PRISMA with t=300 ps (S. Beghini et al.,NIMA 551(2005)364)

- Active area 1000x150 mm2, 200 g/cm2

- 20 time signals shared by 2000 wires of 20 m diameter

- Same characteristics than the small one…

- Detector mechanics and Electronics still to define for spatial reconstruction

LP

GD

/Dit

an

et

WS

11

/20

11

J.

Pa

nc

in

SED for beam tracking Beam tracking mandatory to reconstruct reaction kinematics (resolution of 1.5 mm and 250

ns, high counting rates) Dedicated to heavy nuclei or FF at low energy (<6-7 MeV/n) : SPIRAL2, FAIR, S3 or NFS… Use of a Secondary Electrons Detector with an emissive foil (180 μg/cm2 max (45°) Different topics of work:

Detectors at very low pressure Emissive foil or how to reduce thicknesses: study to perform end of 2011 (<60 μg/cm2 (45°)) Guiding of Secondary Electrons, B field mandatory Electronics

• Construction of 4 low pressure gas prototypes 7×7 cm2 since 2007: 2 wire chambers 1D and 2D and 2 micromegas

• Test benches to mesure spatial and time resolution at CEA Saclay and GANIL

• New electronics based on AFTER design, fitting with GANIL acquisition , for end 2011: AFTER-SED (necessary to qualify the detectors in spatial resolution)

• Test in beam realized in july 2010 on CIME@GANIL

• Real size proto. wire chamber in 2D mid-2011, full characterization for beginning of 2012, prototype shared between NFS and S3

• R&D around micromegas at low pressure still on-going, a real size proto in 2012 depending on the last results

• Test in beam depending on the last results

A. Drouart et al., NIMA579(2007)

J. Pancin et al., JINST4:P12012(2009)

LP

GD

/Dit

an

et

WS

11

/20

11

J.

Pa

nc

in

Test beam at GANIL in july 2010

- Kr from CIME at 1.7 MeV/n from 103 to 105 pps/cm2

- Emissive foil : mylar+Al 180 g/cm2

- No magnetic field

- 3 detectors in coincidence: an MCP first, then a SED and a collimated plastic at the end

- Accurate measurements of time resolution

- Influence of the counting rate on performances

- Tests of a new electronics based on AFTER ASIC

- 3 prototypes to tests: MiniSED, MiniSED2D, MumSED

- In Collaboration with CEA (Saclay) and CNA (Sevilla)

M. Alvarez et al, GANIL/STP226

PLASTIC

collimated

SeD

proto

typ

e

Se-

Emissive foil

Se- M

CP

82Kr

LP

GD

/Dit

an

et

WS

11

/20

11

J.

Pa

nc

in

Prototypes tested in beam 3 prototypes partially tested in lab:− 1 mini-SED “classical”

− 1 mini-SED 2D

− 1 SED with micromegas: time to improve and still spatial to test

LP

GD

/Dit

an

et

WS

11

/20

11

J.

Pa

nc

in

Spatial and time resolutions

SED1D SED2D-1 SED2D-2 mmegasdead layer+drift gaps [mm] 1.2+1.6+1.6 0+0.8+1.6 0+3.2+1.6 0+2.3FWHM [mm] LC 3.5 3.3 4.9 1.9FWHM [mm] HC 4.4 3.5 7.3 *

Profile of the

Plastic coll.FF signal with a SED with the AFTER ASIC

=1.4 mm (No B field)

LP

GD

/Dit

an

et

WS

11

/20

11

J.

Pa

nc

in

Last micromegas results in lab.3 micromegas prototypes tested so far: 128, 256 and 512 m amplification gap

• Good S/N ratio (efficiency with alphas around 40 %), much better than simple PPAC or WC

• Poor energy resolution• Clear influence from ampl. gaps• No so sensitive to ampl. Voltage for

low gaps: α saturation at VLP• Sparking limit due to bulk process

and LP: no real gain at high counting rate…

• Good time resolution (2 mm gap)• PPAC behavior• Spatial resolution to measure

SEDMW

- Not really used at low pressure - Counting rate: same advantages than at

NP ?? - S/N ratio- Time and spatial resolutions

LP

GD

/Dit

an

et

WS

11

/20

11

J.

Pa

nc

in

Real size prototype

- Common proto. between NFS and S3, - SED2D sym. chamber of 201×138 mm2 or 68×47 1D strips- Mounted since sept 2011, tests on time resolution on-going- AFTER-SED ASIC to connect- Spatial resolution to be measured- Mumegas proto. same size beginning of next year (depending on results of

SED2D)

LP

GD

/Dit

an

et

WS

11

/20

11

J.

Pa

nc

in

Conclusion…

Low pressure still widely used at least in nuclear physics

Laboratory tests mandatory (like with other detection system but time consuming)

Secondary Electrons Detectors to produce in the framework of SPIRAL2 or FAIR

S3 and NFS real size prototype to be tested before mid-2012 (micromegas included)

LP

GD

/Dit

an

et

WS

11

/20

11

J.

Pa

nc

in

People involved at CNA, GANIL and CEA/IRFU

Electronics : T. Chaminade, F. Druillole, E. Monmarthe (IRFU) Detector tests : M. Kebbiri (IRFU), S. Damoy (GANIL) Mechanics : M. Riallot (IRFU), G. Fremont (GANIL) Scientific coordinator : M. Alvarez (CNA), H. Savajols, E. Clement, F.

Farget (GANIL), A. Drouart, D. Doré, T. Materna (IRFU) Technical coordinator and analysis : B. Fernandez (CNA) , J. Pancin

(GANIL), T. Papaevangleou (IRFU)

And the others…

LP

GD

/Dit

an

et

WS

11

/20

11

J.

Pa

nc

in

GET

Filter

511 cells

Disc

Pulser

ADC

Slow Control Power

Clock

X 76

Memory Bank

Select External

PA + Filter

Adjustable Sample Size & Frequency ADC parameters

Internal Trigger Calculated Read-Out

Pattern

Pattern/Trigger

PA

PA + Filter 1) 64 +/- input 2) 16 shaping times 3) Adjustable gain/ch