I.Kreslo CHIPP workshop on Detector R&D, University of Geneva, 11-12 June 2008.1

Development of Liquid Nitrogen Time Projection Chambers

A. Ereditato, M. Hess, S. Janoŝ, I. Kreslo, S. Lehmann, M. Messina, U. Moser, B. Rossi, H.-U. Schütz, M. Zeller

Presented by Igor E. Kreslo, Ph.D.LHEP, University of Bern

I.Kreslo CHIPP workshop on Detector R&D, University of Geneva, 11-12 June 2008.2

Multi-energy X-ray cargo radiography – can still something be hidden?

Sensitive to:

Metal objectsHigh density objectsCharacteristic shapes

Not very sensitive to:

Specific chemical composition2D shaped objects (sheet explosives)

I.Kreslo CHIPP workshop on Detector R&D, University of Geneva, 11-12 June 2008.3

Gamma Nuclear Resonant Absorption method of Nitrogen detection(Soreq NRC, 1985)

14N9.17 MeV γ

13C p ~1.5 MeV

I.Kreslo CHIPP workshop on Detector R&D, University of Geneva, 11-12 June 2008.4

Gamma Nuclear Resonant Absorption method of Nitrogen detection(Proposed by Soreq NRC* to US FAA in 1985)

14N

Resonant γ

Detector

14N 13C p

e-

e-

e-

Intensity

N content

e-

e-

e-

Non-Resonant γe-

* Sorec National Research Center, Yavne, 81800, Israel

I.Kreslo CHIPP workshop on Detector R&D, University of Geneva, 11-12 June 2008.5

Detector for GRNA radiography

High spatial resolution (order of 1 mm or better)

Large active volume

High density

High Nitrogen content

TPC on liquidNoble gases(LAr, LXe)

LNitrogen ?

I.Kreslo CHIPP workshop on Detector R&D, University of Geneva, 11-12 June 2008.6

Plans and Perspectives

Ionisation signals in Liquid Argon - Nitrogen

I.Kreslo CHIPP workshop on Detector R&D, University of Geneva, 11-12 June 2008.7

Charge transport in Liquid Argon - Nitrogen

I.Kreslo CHIPP workshop on Detector R&D, University of Geneva, 11-12 June 2008.8

Detector scheme

Electron mobility in Liquid Argon - Nitrogen

I.Kreslo CHIPP workshop on Detector R&D, University of Geneva, 11-12 June 2008.9

LAR TPC prototype

Mixture LAr-LN is prepared directly in the cryostat. The content of Nitrogen is monitored by density sensor.ρLAr = 1.4 g/cm3

ρLN = 0.8 g/cm3

Density sensor:

Floater

C = f(ρ)

I.Kreslo CHIPP workshop on Detector R&D, University of Geneva, 11-12 June 2008.10

LAR TPC prototype

8mm

100 x 100 mm

Wire pitch2 mm

To preamp

HV power supply0-30kV

I.Kreslo CHIPP workshop on Detector R&D, University of Geneva, 11-12 June 2008.11

LAr TPC prototype

Argon used: Carbagas 1, Commercial grade “48” ( < 2*10-7 impurities concentration)

Nitrogen used: Carbagas, Commercial grade “50” ( < 10-7 impurities concentration)

No additional purification is done for the first tests.

1 Carbagas, Hofgut, 3073 Gumligen , Switzerland

I.Kreslo CHIPP workshop on Detector R&D, University of Geneva, 11-12 June 2008.12

LAR TPC prototype and performance

Detector readout, amplifier, DAQ

CAEN V1724 VME 8xADC

Shaping Q-integrating preamplifier, ~ 25 mV/fC

Wire chamber

I.Kreslo CHIPP workshop on Detector R&D, University of Geneva, 11-12 June 2008.13

LAR TPC prototype and performance

Muon

0-30 kV

I.Kreslo CHIPP workshop on Detector R&D, University of Geneva, 11-12 June 2008.14

LAR TPC prototype and performance

Cosmic Muon Tracks recorded

~ 5 mm drift

I.Kreslo CHIPP workshop on Detector R&D, University of Geneva, 11-12 June 2008.15

I-

LAr TPC prototype and performance

TPC response to a primary ionization

Particle

Ar+ e-

Ar+ e-

E

Recombination losses q0=A*Q0

Primary ionisation Q0

e-

Attachment

losses q=q0e -(D/λ)

collection wires

D, drift distance

I-

I-

I.Kreslo CHIPP workshop on Detector R&D, University of Geneva, 11-12 June 2008.16

LAR TPC prototype and performance

TPC response to a Compton electrons - simulation

Losses during the charge drift affect the shape of the spectrum, but not the end point !

End point can be used to measure recombination.

I.Kreslo CHIPP workshop on Detector R&D, University of Geneva, 11-12 June 2008.17

LAR TPC prototype and performance

TPC response to Compton electrons from 60Co (1.17 and 1.33 MeV gammas)(measured data)

I.Kreslo CHIPP workshop on Detector R&D, University of Geneva, 11-12 June 2008.18

LAR TPC prototype and performance60Co (1.17 and 1.33 MeV gammas)

“Box model” :

I.Kreslo CHIPP workshop on Detector R&D, University of Geneva, 11-12 June 2008.19

LAR+N TPC prototype and performance

A=1

Recombination vs Nitrogen content (vol. %)

60Co (1.17 and 1.33 MeV gammas)

I.Kreslo CHIPP workshop on Detector R&D, University of Geneva, 11-12 June 2008.20

LAR+N TPC prototype and performance

A=1

A~0.5

Recombination vs Nitrogen content, (vol. %)

I.Kreslo CHIPP workshop on Detector R&D, University of Geneva, 11-12 June 2008.21

LAR+N TPC prototype and performance

A=1

A~0.5

Recombination vs Nitrogen content, (vol. %)

Similar effect was observed by D.W. Swan in 1963, with about 0.6 vol. % of LN ( for reference see slide 7) but not explained !

I.Kreslo CHIPP workshop on Detector R&D, University of Geneva, 11-12 June 2008.22

LAR+N TPC prototype and performance

Box model parameters evolution with LN content (vol. %)

Bet

ha

A

I.Kreslo CHIPP workshop on Detector R&D, University of Geneva, 11-12 June 2008.23

LAR+N TPC first test conclusions

1. First prototype TPC with Liquid Argon-Nitrogen mixture operates well in Bern.

2. Collected charge at 8 mm drift and 6 vol. % of Nitrogen is sufficient to see MIPs and 1 MeV electrons (signal / noise >10).

3. At 6% of Nitrogen such TPC is already more efficient for GRNA, than liquid scintillator detectors.

4. Further study on recombination mechanisms in LAr-N is needed.

5. The technology is very promising for security applications !

I.Kreslo CHIPP workshop on Detector R&D, University of Geneva, 11-12 June 2008.24

LAR+N TPC Plans and Perspectives

1. More detailed study on recombination vs Nitrogen content with non-resonant gammas.

2. Study of charge attachment cross-section vs Nitrogen content.

3. Proton - electron separation study (simulation)

4. Tests with resonant gammas on a proton accelerator.

5. Optimization of the detector geometry for GRNA scenario.

6. Contacts with industry - building a cargo screener prototype