new ionization chamber technology

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NEW NEW Ionization Chamber Technology Anne Dabrowski Results on behalf of Mayda Velasco’s Hardware Research group. P. Ball 3 , A. Darowski 1 , G. Graham 3 , C. Kendziora 2 , F. Krueger 2 G. Tassotto 2 , G. Ünel 1 , M. Velasco 1 1 Northwestern University, 2 Fermilab, 3 Richardson Electronics Lunch Bag Seminar 1 May 2002

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NEW Ionization Chamber Technology. Anne Dabrowski Results on behalf of Mayda Velasco’s Hardware Research group . P. Ball 3 , A. Darowski 1 , G. Graham 3 , C. Kendziora 2 , F. Krueger 2 G. Tassotto 2 , G. Ünel 1 , M. Velasco 1 - PowerPoint PPT Presentation

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Page 1: NEW  Ionization Chamber Technology

NEWNEW Ionization Chamber Technology

Anne Dabrowski

Results on behalf of Mayda Velasco’s Hardware Research group.

P. Ball 3, A. Darowski 1, G. Graham 3, C. Kendziora 2, F. Krueger 2

G. Tassotto 2, G. Ünel 1, M. Velasco 1

1 Northwestern University,2 Fermilab,3 Richardson Electronics

Lunch Bag Seminar 1 May 2002

Page 2: NEW  Ionization Chamber Technology

Northwestern High Energy Physics

Why the need for new Hardware?

• Modern High Energy Experiments – High intensity beams > 1011 particles/ micro

second– Radiation Hard– Once-off calibration– Monitor beam line position / background

particle flux

Page 3: NEW  Ionization Chamber Technology

Northwestern High Energy Physics

• Solution:– Ceramic radiation hard ionization chambers.

– Either Gas sealed or Vacuum – SEM (secondary

emission monitor)

Q = I * d * e*A * n * M current read by chamber

I – beam intensity (cm-2 s-1) (<1011 cm-2 s-6)

d – gap size (cm) (~1mm)

e – electron charge

M – multiplication factor (~1)

N – tot num of ion/electron pair/cm (8 for He at atm 98 for Ar at 1 atm)

A – elecrode area (cm2) (1 cm2)

Page 4: NEW  Ionization Chamber Technology

Northwestern High Energy Physics

Basic Description of Design

• Chamber filled with Gas -- Ionization SIC (< 1011/p/cm2/s)• Chamber in Vacuum -- Secondary Emission Monitor SEM (above 1010 /p/cm2/s)

Page 5: NEW  Ionization Chamber Technology

Northwestern High Energy Physics

Basic Chamber Design

•Fixed volume, Temperature and Pressure changes do not affect calibration•Radiation Hard Materials (> 1010 Rads) – Ceramic (AL2O3, 94%, 96%) – Kovar (nickel, iron, cobalt)

Page 6: NEW  Ionization Chamber Technology

Northwestern High Energy Physics

Engineering drawing

Tolerances:

•Gap = 1mm +/- 0.001”

•guard-to-collector = 0.5 mm+/- 0.002”

•Flatness 0.001”

Page 7: NEW  Ionization Chamber Technology

Northwestern High Energy Physics

SIC prototypes

Page 8: NEW  Ionization Chamber Technology

Northwestern High Energy Physics

Timeline for Design Development• 2000 Richardson Electronics (REL) made Glass Chambers

(Inspired by V. Falaleev Design). – Detection observed– Design studies– Change to ceramic because of high tolerances

• Ceramic design – Electrode changed from round edges to edges square D1 – D2– Flat for signal collector & guard ring.

• Multiple chambers produced (7 in all)– gas refilling tested.– Found occasional shorts on due to metal filings inside the chamber…

tooling redesign.

• Believe have the final design– (testing by producing several chambers….already under construction).

• successful– mass production will start at the rate of 10 chambers/week.

Page 9: NEW  Ionization Chamber Technology

Northwestern High Energy Physics

How do they Behave ?

Electron SourceI ~e8 - e9

ATF(BN L)

Photon Em ission424 R /hr

R adiation C alib ration Facility(FN AL)

Proton Source1e11 - 1e12

Booster(FN AL)

P rev iew T E S T IN G fac ilities

Page 10: NEW  Ionization Chamber Technology

Northwestern High Energy Physics

Radiation Physics Calibration Facility (RPCF)

Photon Emission 424 R/hr

• Check chamber quality– Plateau, ionization response, reproducibility

• Lead to design improvements

• Determined operational modes– operational voltage, gain voltage, gas type

• Do pre-calibration before operating in other facilities.

Page 11: NEW  Ionization Chamber Technology

Northwestern High Energy Physics

Radiation Physics Calibration Facility (RPCF,FNAL)

“Flat mounting”

“Side Mounting”

•Two new Cs137 sources:

•Max:1600 Rad/Hr

•The old source was

•424 Rad/Hr

Page 12: NEW  Ionization Chamber Technology

Northwestern High Energy Physics

Results (RPCF)Note Slope !!

Electrode edges

Page 13: NEW  Ionization Chamber Technology

Northwestern High Energy Physics

What Changed?Design 1 vs. Design 2

The electrode edge … Curved Flat

Effected slope of plateau … reduced by ~ 70 %

Page 14: NEW  Ionization Chamber Technology

Northwestern High Energy Physics

Results D2 vs. D4 Signal

> Electrode area

Page 15: NEW  Ionization Chamber Technology

Northwestern High Energy Physics

Setup to test chambers at the RPCF– pre-calibration for all SICs

•Investments: A Keithly

electrometer

•Sensitivity 2 nC

•Resolution of 0.1 pC

•Bias current of < 3fA

•Output of electrometer via GPIB to computer running LabView to a data file.

•Procedure almost automatic Good for grad students when calibrating in the summer

Page 16: NEW  Ionization Chamber Technology

Northwestern High Energy Physics

Chamber Characterization show no radiation damage after XX protons

Chamber filled withHe for more than a year

No change…

Reproduce calibrations

Page 17: NEW  Ionization Chamber Technology

Summary of RPCF Results:

• Good reproducibility

• Can measure both small and large currents.

•Keithley Electrometers and Powers Supplies allows to do good measurements of knee of plateau need to test gas quality of chambers… no degradation see so far.

•LABview DAQ – user enter customized measurement parameters – automated DAQ

•Slopes good – but not quite flat… we believe we understand it.

Page 18: NEW  Ionization Chamber Technology

Northwestern High Energy Physics

Tests at ATF (BNL) low energy electron

beam No saturation below 8*109/p/cm2

Page 19: NEW  Ionization Chamber Technology

Booster (FNAL) proton source ~1e9 to 1e12

Old Toroid only for Flux measurement

New Toroid +chamber for Flux measurement &

Longitudinal movement for alignment

SIC Only1mm Wire Chamber & SIC

Page 20: NEW  Ionization Chamber Technology

Booster (FNAL) HaloHigh intensity ~ 1e9 proton source

1.5 s per spill … halo see 1/100 of total beam

ONLINE OFFLINE

Page 21: NEW  Ionization Chamber Technology

Northwestern High Energy Physics

Booster (FNAL)Plateau in the beam (1.8e11)---saturation (same effects present with design 4) shortens plateau—space charge

Page 22: NEW  Ionization Chamber Technology

Northwestern High Energy Physics

Booster (FNAL) – Intensity Scan

SEM-like SIC-like

No saturation even At 1012 ppp(10-5 torr)

Clear …Saturation

Page 23: NEW  Ionization Chamber Technology

Northwestern High Energy Physics Chamber see about 40%

Of the beam

Beam Moved

Need to repeatWith vertical movement

Beam Profile fromWire chamber

Page 24: NEW  Ionization Chamber Technology

Northwestern High Energy Physics

Summary of results from Booster Saturate above e11 in SIC-mode, but no

saturation in SEM-mode.

• When making plateaus: gain observed at 200 V in the beam center, but not seen at 350 V in the “halo” like in the RPCF tests

• use SWIC electronics for both low and high currents just change capacitors

• So far no signs of radiation damage … or helium leakage

• To do… add vertical movement to get proper alignment.

Page 25: NEW  Ionization Chamber Technology

Northwestern High Energy Physics

Secondary Emission Monitor– SIC chamber in vacuum

•Getter - Place a strip of barium under the collector and activate it at about 1000 degree C.

•Ion Bombardment - Apply a voltage across the electrodes while pumping for reducing atmosphere of H2.

–Richardson used this process on vacuum tubes to 10-8 torr

This look like a very promising way of operating The chambers for >1011 ppp

Page 26: NEW  Ionization Chamber Technology

Northwestern High Energy Physics

Permeation Test– test run for 3-4 days … Helium is not leaking….

• The ion chamber was then put in side of a small vacuum chamber and tested using a Dupont Mass Spectrometer leak detector the total leak rate was found to less than 2X10 –10 STD CC P/S.

• Then the temperature was raised slowly to 100 degree C.

• Max leak rate < 40X10 –10 STD CC P/S

Page 27: NEW  Ionization Chamber Technology

Northwestern High Energy Physics

Conclusion

Believe to have a working design that can be operated at :

• I<1011 ppp in SIC-mode• I>1010 ppp in SEM-mode

200 chambers to be build with the new tooling design.