Michal Pomorski - GSI · Michal Pomorski, CEA-LIST, Diamond Sensors Laboratory, ADAMAS 3rd, Trento 19/11/2014 Co-Authors Co-Authors (CEA Saclay): Christine Mer-Calfati Francois Foulon

Michal Pomorski, CEA-LIST, Diamond Sensors Laboratory, ADAMAS 3rd, Trento 19/11/2014

Diamond as a solid state micro-fission chamber for thermal neutron detection

Michal Pomorski CEA-LIST , Diamond Sensors Laboratory, France

3rd ADAMAS Collaboration Meeting @ ECT* 18-20 November, 2014

Trento


Co-Authors

Co-Authors (CEA Saclay):

Christine Mer-Calfati Francois Foulon

Many thanks to VR1 reactor team in Prague:

Lubomir Sklenka Tomas Bily Jan Rataj

and others…..

open access facility: [email protected]

request form: reactorvr1.eu/download/request_for_access.pdf

mailto:[email protected]

http://reactorvr1.eu/download/request_for_access.pdf


❑ Motivation / Previous work

❑ Diamond Samples / Pre-testing

❑ Set-up ❑ VR1 reactor in Prague ❑ U-235 + diamond detectors + electronics

❑ Some results ❑ fission fragments spectra ❑ linearity with flux, core-mapping ❑ TCT signals + other observations……

❑ Summary

Outline


Motivation/Previous workneutron detection with diamond detectors

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Bergonzo et al.


Motivation/Previous workthermal neutron detection

otherwise mentioned. (In one sample, 5% of HDPE wasadded to a Al2O3:C and 6LiF mixture to increase thestrength of the pellet. In this case, HDPE was not usedas a neutron converter, but because of the mechanicalproperties.) The dimensions of the pellets are !6.4 mm indiameter and !0.5 mm of thickness. Before irradiationthe dosimeters were zeroed by bleaching with a light froma halogen lamp filtered by a yellow Kopp 3-69 filter.

2.2. Irradiation facilities

An uncalibrated Pu–Be source was used for initial com-parison of the neutron response for various mixtures ofAl2O3:C with neutron converters. The source is mountedinside a container filled with paraffin used for moderatingthe neutrons. For the irradiations, the samples were placedin a holder and introduced inside the paraffin container.Since the actual spectrum and dose rate at the sample posi-tion are unknown, this source was used exclusively to com-pare the properties of different materials or samples.Typical neutron spectrum of a Pu–Be source can be foundin [6,19].

Neutron irradiations were also performed at the SCK-CEN (Belgium Nuclear Research Institute) using a bare252Cf source traced to primary standard in UK NationalPhysics Laboratory (NPL). The SCK-CEN irradiationfacility is described in [20]. The dimensions of the roomare 6 m · 6 m · 3.5 m (height). During irradiation, thesource is positioned in one of the corners, at 1.4 m fromthe walls and 1.2 m from the floor. A 30 cm · 30 cm ·15 cm PMMA phantom was installed in the diagonal ofthe room, the side facing the source located at 75 cm or1.5 m from the 252Cf source, depending on the experiment.The dosimeters were centered on the face of the phantomthat is oriented towards the source, no less than 10 cm fromthe edge of the phantom. The dosimeters and the center ofthe phantom were at the same height as the source. Thedose equivalent rates were 6.9 mSv h"1 and 1.7 mSv h"1

at 75 cm and 1.5 m from the source, respectively, not con-

sidering the contribution from room scattering. The uncer-tainty on these values is of the order of 4% (1r interval).The typical spectrum of a 252Cf source is given by ISO8529-1 [21] and the spectrum of the source in the calibra-tion room simulated by Monte Carlo is given in [20]. Thephoton dose equivalent for a bare 252Cf source is !5% ofthe neutron dose equivalent [22]. All reported neutrondoses are personal dose equivalent at a depth of 10 mm,Hp(10).

The contribution of room scattering to the dosimeterreading was evaluated using the shadow cone technique[23]. The shadow cone from SCK-CEN consists of a 20-cm long front end made of iron followed by a 30-cm longboron-loaded polyethylene section [20]. The diameter ofthe shadow cone increases linearly from 3.5 cm on the sidefacing the source to 15 cm on the opposite side. With thephantom at 1.5 m from the source, the cone cast a shadowthat covers the 30 cm · 30 cm phantom almost completely,except for the outermost part of the corners. For near doseequivalent ambient neutron monitors, like the Studsvik2202D, the response due to scattered radiation is 33% ofthe total response [20].

Additional irradiations were performed with a 60Cogamma source at SCK-CEN, traced to primary standardfrom the Physikalisch-Technischen Bundesanstalt (PTB),Germany.

2.3. OSL readout

The OSL readouts were carried out using an automatedRisø reader TL/OSL-DA-15 [24] equipped with greenLEDs (broad band emission centered at 525 nm) for opticalstimulation, a bi-alkali PMT (model 9235QB from ElectronTubes, Inc.) for light detection and an integrated 90Sr/90Ybeta source for additional irradiations. For the OSLmeasurements, Hoya U-340 filters (7.5 mm thickness, trans-mission between 290 and 390 nm) were used in front ofthe PMT to discriminate the luminescence against thestimulation light. For TL measurements of TLD-600 andTLD-700 detectors, BG-39 filters (8.0 mm thickness, trans-mission between 340 and 600 nm) were used in front of thePMT.

The OSL readout sequence consisted first of stimulatingthe crystal for 600 s to measure the OSL curve of the irra-diated dosimeter. This was followed by irradiation withthe reference dose from 90Sr/90Y source and anotheroptical stimulation for 600 s to measure the OSL curveproduced by the reference irradiation. The first and thesecond OSL curves were integrated over the 600 s ofoptical stimulation to obtain respectively S and SR, whereS is the OSL signal produced by the radiation field to bemeasured and SR is the OSL signal produced by the refer-ence irradiation. The reference irradiation was used toaccount for variations in the dosimeter mass or intrinsicsensitivity. In all cases the background signal due toPMT dark counts was subtracted from the total measuredOSL signal.

Table 1Main isotopes used as neutron converters in luminescence detectors andcorresponding natural abundance, thermal neutron cross-section andproducts [6,9]

Isotope Naturalabundance(%)

r*

(barns)Products

6Li 7.4 940 3H (2.75 MeV) + 4He (2.05 MeV)

10B 19.8 3840 7Li (1.0 MeV) + 4He (1.8 MeV)7Li (0.83 MeV) + 4He (1.47 MeV)+ c (0.48 MeV)

157Gd 15.7 255,000 158Gd + cs + conversion e"

+ X-rays (29–182 keV)


+ X-rays (39–199 keV)

J.C.R. Mittani et al. / Nucl. Instr. and Meth. in Phys. Res. B 260 (2007) 663–671 665

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http://www-norhdia.gsi.de/talks/4th/G_Verona-Rinati.pdf

Single crystal CVD diamond neutron detectors in a p-type/intrinsic/metal layered structure - Gianluca Verona-Rinati, Uni Roma Tor Vergata

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otherwise mentioned. (In one sample, 5% of HDPE wasadded to a Al2O3:C and 6LiF mixture to increase thestrength of the pellet. In this case, HDPE was not usedas a neutron converter, but because of the mechanicalproperties.) The dimensions of the pellets are !6.4 mm indiameter and !0.5 mm of thickness. Before irradiationthe dosimeters were zeroed by bleaching with a light froma halogen lamp filtered by a yellow Kopp 3-69 filter.

2.2. Irradiation facilities

An uncalibrated Pu–Be source was used for initial com-parison of the neutron response for various mixtures ofAl2O3:C with neutron converters. The source is mountedinside a container filled with paraffin used for moderatingthe neutrons. For the irradiations, the samples were placedin a holder and introduced inside the paraffin container.Since the actual spectrum and dose rate at the sample posi-tion are unknown, this source was used exclusively to com-pare the properties of different materials or samples.Typical neutron spectrum of a Pu–Be source can be foundin [6,19].

Neutron irradiations were also performed at the SCK-CEN (Belgium Nuclear Research Institute) using a bare252Cf source traced to primary standard in UK NationalPhysics Laboratory (NPL). The SCK-CEN irradiationfacility is described in [20]. The dimensions of the roomare 6 m · 6 m · 3.5 m (height). During irradiation, thesource is positioned in one of the corners, at 1.4 m fromthe walls and 1.2 m from the floor. A 30 cm · 30 cm ·15 cm PMMA phantom was installed in the diagonal ofthe room, the side facing the source located at 75 cm or1.5 m from the 252Cf source, depending on the experiment.The dosimeters were centered on the face of the phantomthat is oriented towards the source, no less than 10 cm fromthe edge of the phantom. The dosimeters and the center ofthe phantom were at the same height as the source. Thedose equivalent rates were 6.9 mSv h"1 and 1.7 mSv h"1

at 75 cm and 1.5 m from the source, respectively, not con-

sidering the contribution from room scattering. The uncer-tainty on these values is of the order of 4% (1r interval).The typical spectrum of a 252Cf source is given by ISO8529-1 [21] and the spectrum of the source in the calibra-tion room simulated by Monte Carlo is given in [20]. Thephoton dose equivalent for a bare 252Cf source is !5% ofthe neutron dose equivalent [22]. All reported neutrondoses are personal dose equivalent at a depth of 10 mm,Hp(10).

The contribution of room scattering to the dosimeterreading was evaluated using the shadow cone technique[23]. The shadow cone from SCK-CEN consists of a 20-cm long front end made of iron followed by a 30-cm longboron-loaded polyethylene section [20]. The diameter ofthe shadow cone increases linearly from 3.5 cm on the sidefacing the source to 15 cm on the opposite side. With thephantom at 1.5 m from the source, the cone cast a shadowthat covers the 30 cm · 30 cm phantom almost completely,except for the outermost part of the corners. For near doseequivalent ambient neutron monitors, like the Studsvik2202D, the response due to scattered radiation is 33% ofthe total response [20].

Additional irradiations were performed with a 60Cogamma source at SCK-CEN, traced to primary standardfrom the Physikalisch-Technischen Bundesanstalt (PTB),Germany.

2.3. OSL readout

The OSL readouts were carried out using an automatedRisø reader TL/OSL-DA-15 [24] equipped with greenLEDs (broad band emission centered at 525 nm) for opticalstimulation, a bi-alkali PMT (model 9235QB from ElectronTubes, Inc.) for light detection and an integrated 90Sr/90Ybeta source for additional irradiations. For the OSLmeasurements, Hoya U-340 filters (7.5 mm thickness, trans-mission between 290 and 390 nm) were used in front ofthe PMT to discriminate the luminescence against thestimulation light. For TL measurements of TLD-600 andTLD-700 detectors, BG-39 filters (8.0 mm thickness, trans-mission between 340 and 600 nm) were used in front of thePMT.

The OSL readout sequence consisted first of stimulatingthe crystal for 600 s to measure the OSL curve of the irra-diated dosimeter. This was followed by irradiation withthe reference dose from 90Sr/90Y source and anotheroptical stimulation for 600 s to measure the OSL curveproduced by the reference irradiation. The first and thesecond OSL curves were integrated over the 600 s ofoptical stimulation to obtain respectively S and SR, whereS is the OSL signal produced by the radiation field to bemeasured and SR is the OSL signal produced by the refer-ence irradiation. The reference irradiation was used toaccount for variations in the dosimeter mass or intrinsicsensitivity. In all cases the background signal due toPMT dark counts was subtracted from the total measuredOSL signal.

Table 1Main isotopes used as neutron converters in luminescence detectors andcorresponding natural abundance, thermal neutron cross-section andproducts [6,9]

Isotope Naturalabundance(%)

r*

(barns)Products

6Li 7.4 940 3H (2.75 MeV) + 4He (2.05 MeV)

10B 19.8 3840 7Li (1.0 MeV) + 4He (1.8 MeV)7Li (0.83 MeV) + 4He (1.47 MeV)+ c (0.48 MeV)


+ X-rays (29–182 keV)


+ X-rays (39–199 keV)

J.C.R. Mittani et al. / Nucl. Instr. and Meth. in Phys. Res. B 260 (2007) 663–671 665

Only one publication with FF and natural diamond (half page) ~ 1970… +previous work of Christine Mer et. al. thick pcCVD+EGscCVD + high power reactor

Idea: Use of fissile material as a converter eg.: Uranium-235 —> 584 barns for fission


.Diamond Samples

Optical Grade scCVD e6 (OGscCVD) p+-intrinsic-metal structure CEA (PIM)

[N0] =< 1ppm thickness = 17 microns size= 3 x 3 mm (broken) contacts = Al (1mm diam.)

[N0] << 1ppm thickness ~ 20 microns (intr.) size= 3 x 3 mm contacts = Cr/Au (<1mm diam.)

Cr(50nm)/Au(100nm)

intrinsic scCVD

p+-B dopedCVD(1micron)HPHT

OG scCVD

Al (100nm)

Al (100nm)


Alpha SpectraLaboratory Pre-testing

0 200 400 6000.0

0.2

0.4

0.6

0.8

1.0

1.2

direct 5m BNC

counts/max

channel no.

PiM @ +30 V (1.5 V/µm)

479

0 200 400 6000.0

0.2

0.4

0.6

0.8

1.0

1.2

direct 5m BNC

counts/max

channel no.

opt. scCVD ~17µm @ +170 V(10V/µm)

468

Am-241 alpha spectra 5.486 MeV in vacuum, using CSA (3micros shaping)

OGscCVD PiM


AlphaTCTLaboratory Pre-testing

-20 0 20 40 60 80

0.0

0.1

0.2

0.3

optscCVD @ 170 V PiM @ 30 V

sign

al @

50

Ohm

[V]

time [ns]

TCT (50 Ohm) from 5.48 MeV alphas, CIVIDEC

-2 -1 0 1 2 3 4 50.0

0.1

0.2

0.3

optscCVD @ 170 V

sign

al @

50

Ohm

[V]

time [ns]


-20 0 20 40 60 80

0.00

0.05

PiM @ 30 V

sign

al @

50

Ohm

[V]

time [ns]


PiM, Claudio Verona Tor Vergata Univ.Rome

buried p+

buried p+

0 5 10 15 200.0

0.1

0.2

0.3

0.4

0.5

0.6

sign

al a

mpl

itude

on

50 O

hm [V

]

time [ns]

TCT signals

laser power

25%

p+ on top


VR1 reactor in Prague

VR1 in-core fluxes correspond to external for HP reactors

- low power research reactor (max 1kW, 1^10 n/cm2s@500W) - light water (reflector, shielding, cooling) - no thermal effects….

diamond detectors


U-235 + Diamond Detectors + Electronics

U-235

17microns OG scCVD 20 microns PIM scCVD

thermal neutrons

5m of BNC

in-core

CSA CSA

DAQ DAQ

fission fragments

bias voltages on read-out electrodes: OGscCVD +170V(10V/micron) (h-drift) PiM + 30V(~1.5V/micron) (h-drift)

PiM

OGscCVD

Emplacement pastille d’uranium

Emplacement collimateur

quantité de matière activable doit donc être limitée dans le dispositif pour qu’à l’issu des irradiations sous ULYSSE, le temps de désactivation (lié à la période radioactive du matériau) ne soit pas trop élevé.

V-1 Préparation des diamants et des convertisseurs

Les contacts en or (utilisés pour la caractérisation sous alpha) des diamants pré-caractérisés sont dissous (à l’aide d’une eau régale) puis redéposés par évaporation afin d’obtenir des plots de même surface.

Une couche de bore de 600 µm est déposée par évaporation au dessus d’une majeure partie du plot en or du diamant monocristallin T8 et du diamant CVD1 pour le diamant polycristallin. La partie du plot sans bore permettra de relier le fil en or afin de polariser le diamant. L’uranium ne peut pas être déposé par évaporation en raison de sa radioactivité. Il se présente sous forme de pastille sur laquelle est réalisé un dépôt d’uranium. La pastille est entourée de plastique, seul le dépôt est à nu.

FIG : Pastille d’uranium

Un support en téflon (non activable) à deux étages est réalisé pour le diamant T8 permettant de positionner un collimateur et la pastille d’uranium au dessus du diamant. Un autre support à un seul étage, pour la pastille d’uranium, est réalisé pour le détecteur CVD2. Le collimateur permettra de collimater les fragments de fission issus de l’uranium pour le diamant monocristallin. En revanche, pour les diamants associés au bore, les neutrons ne peuvent pas être collimatés.

FIG : Support en téflon

V-2 Montage du boîtier

Les boîtiers sont en graphite (non activable), munis de deux trous pour pouvoir faire passer les câbles dénudés amenant la haute tension (HT) et permettant de récupérer les impulsions. Les diamants sont collés avec de la pâte à l’argent sur une plaque de circuit imprimé. Des « protections » en téflon sont positionnées sous le fil d’or pour éviter que celui-

U-235

1 cm

no collimator used


U-235 + Diamond Detectors + Electronics

+ alpha decay with 4.679 MeV

U-235 fission

after 5mm air (rough estimation) ~80 MeV Kr (~110 MeV) ~35 MeV Ba (~60 MeV)

17 microns 17 microns

Ba-56@60MeV Kr-36@110MeV

average energy to fission fragments ~170 MeV


Fission Fragments Spectra

0 200 400 600 800 10000.0

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0.8

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1.2

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norm

aliz

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ount

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channel number

lighterFF heavierFF

lighterFF/higherE

heavierFF/lowerE

average energy to fission fragments

~170 MeV

gamma bckg.


Fission Spectra with Increasing Power

0 200 400 600 800 1000100

101

102

103

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105

500 W 100 W 10 W 1 W 0.1 W 0.01 W

counts/channel

ADC channel number0 200 400 600 800 1000

100

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105 0.01 W 0.1 W 1 W 10 W 100 W 500 W

counts/channel

ADC channel number

OGscCVD PiM

alpha-peak@~4.679MeV100W ~ 2E9 n/cm2.s (core center)~ 10 min acquisition time


Linearity with Flux

104 105 106 107 108 10910-2

10-1

100

101

102

103

diam

ond

dete

ctor

[cps

]reactor diagnostics [cps]

Equation y = a + b*x

Weight No Weighting

Residual Sum of Squares

5.1638E-4

Pearson's r 0.99998

Adj. R-Square 0.99996Value Standard Error

DIntercept -5.50928 0.01886Slope 1.00538 0.00283

σ0.3%R20.9999

104 105 106 107 108 109

10-1

100

101

102

103

diam

ond

dete

ctor

[cps

]

reactor diagnostics [cps]

Equation y = a + b*x

Weight No Weighting

Residual Sum of Squares

0.00337

Pearson's r 0.99989

Adj. R-Square 0.99973Value Standard Error

D1Intercept -5.10035 0.04817Slope 0.98325 0.00724

threshold @ 200 ch

σ0.7%R20.9997

OGscCVD PiM


Core-Mapping

0

10

20

30

40

50

60

70

80

0.0 5.0x103 1.0x104 1.5x104 2.0x104

integrated counts diamond detector

dist

ance

from

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chan

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otto

m [c

m]

0

10

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0.0 4.0x103 8.0x103 1.2x104

integrated counts diamond detector

dist

ance

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m[c

m]

PiMOGscCVD@100W


Core-Mapping

0

10

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0.0 0.2 0.4 0.6 0.8 1.0counts normalized @ 30 cm

dist

ance

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m [c

m]

0

20

40

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100

0.0 0.2 0.4 0.6 0.8 1.0

He3 PiM OGscCVD

counts normalized @ 30 cm

dist

ance

from

the

chan

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m [c

m]

OGscCVD + PiM OGscCVD + PiM + He3

@100W


Gamma Background

OGscCVD PiM

0 200 400 600 800 10001

10

100

1000

counts/channel

channel number

100 W 10 W 1W

0 200 400 600 800 10001

10

100

counts/channel

channel number

1 W 10 W 100 W


TCT Signals for OGscCVD

y 100mV/div ; x 10ns/div y 2mV/div ; x 5ns/div

350 MHz DSO@50 Ohm + 5m BNC

CIVIDEC 40dB amplifier no amp, just bias-T


Priming of OGscCVDSome More Observations

0 50 100 150 2000

50

100

counts

channel number0 50 100 150 200

50

100

150

counts

channel number

γ-priming (?)

235U α-particles 4.679 MeV

OGscCVD PiM (no priming)


Polarisation of OGscCVD@-170V majority of e-driftSome More Observations

0 200 400 600 800 1000

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TAG

TAG

TAG

TAG

TAG

channel number

counts

time

0 200 400 600 800 1000 12000

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250

300

350

counts/channel

channel number

e-drift

final state (stable)

strong electron trapping in OGscCVD…..


Radiation Hardness Issue

1E14 1E15 1E1650

60

70

80

90

100

Polycristalline diamond with boron converter Polycristalline diamond with Uranium converter Single crystall diamond with Uranium converter

Rela

tive

decr

aese

of t

he p

ositi

on p

ic %

neutron fluence (neutron/cm2)

However, radiation hardness limits : Comparison of the signal loss between single crystal detector and poly X detector with neutron fluence

Æ Degradation of the homoepitaxial diamond detector at lower neutron fluences than polycristalline diamond

1- Thermal Neutron detection

U+MonoX

B+polyX

U+polyX

From previous work, Christine Mer et. al MonoX=EGscCVD ~200 microns thick

should be better for thin detectors, and even better for membranes………


Summary and Outlook

What can be ‘easily’ improved: - sensitivity/count rate x100 —> larger samples+contact size+sandwich conf. - larger TCT signals —> better electronics, U-235 precipitation on diamond

- (Philippe talk) - better gamma/neutron ratio —> U-235 electro-precipitation on diamond - improved RH —> membrane OGscCVD, thinner i-layer = no implantation

- use of U-235 as converter material - with FF of high energy - diamond micro-fission chamber based on ‘cheap’ OG material concept proved:

- stable operation (FF up to 5kHz tested), perfect linearity - high n/gamma ratio - possibility to operate with no amps…maybe HTemp etc……

some open questions: - sensitivity, RH


In-core thermal neutron monitoringFirst Applications

Diamond as micro solid-state fission chamber:

U-235

17microns OG scCVD 20 microns PIM scCVD

thermal neutrons

5m of BNC

in-

CSA CSA

DAQ DAQ

fission fragments

VR1 training reactor in Prague

U-235- lower crossection, but heavy fragments large signal, better n/gamma ratio, no-amplifiaction needed

facility with open access please contact:[email protected]


In-core thermal neutron monitoring

average energy fission fragments

~170 MeV

0 50 100 150 200

50

100

150

coun

ts

channel number

γ-priming (?)

235U α-particles 4.679 MeV

0 50 100 150 2000

50

100

coun

ts

channel number

Fig. X. Uranium alpha peak 4.3 MeV for both detectors [left] OPT-scCVD, residual priming is visible at 1e7 alpha peak shifts right, reaching 100% CCE, similar to PIM-scCVD [right] PIM-scCVD, stable detection from the beginning no priming

0 200 400 600 800 1000

0

24

48

72

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TAG

TAG

TAG

TAG

TAG

channel number

coun

ts

Z Axis

Title

0 200 400 600 800 1000 12000

50

100

150

200

250

300

350

TAG

(DES

CRIP

TIO

N)

Row Numbers

TAG

Fig. X Polarization phenomenon for OPT-scCVD, negative bias -170 V, majority of electrons drift

0 200 400 600 800 10000.0

0.2

0.4

0.6

0.8

1.0

1.2

OG diamond PIM

norm

alize

d co

unts

channel number

Fig. X Fission fragments spectra for both detectors, better performane of OPT-scCVD is evidenced, most probably due to thinner Al contacts (Au in case of PIM-scCVD) and/or high bias operation [OPT-scCVD@10V/micron, PIM-scCVD@2V/micron]

4e Gamma background

0 200 400 600 800 10001

10

100

1000

coun

ts

channel number

100 W 10 W 1W

0 200 400 600 800 10001

10

100

coun

ts

channel number

1e7 1e6 1e5

Fig. X [left] OPT-scCVD [right] PIM-scCVD

4 Transient Current signals

OPT-scCVD – optical grade e6 single crystal CVD diamond, metalized with Al ~100nm, 2 mm in diameter

front contact, 17 microns thick

PIM-scCVD – electronic grade scCVD diamond grown in the Diamond Sensors Laboartory of CEA-Saclay.

Detector’s structure includes: HPHT substrate, p+ CVD diamond layer, which serves as a back contact 1-3

microns thick, intrinsic CVD layer >14 microns(?) thick

3c electronics

- 5m cable, Amptek, A250 charge sensitive amplifier, Ortec shaper, HV voltage unit, pocket M8000

ADC

- Cividec 50 Ohm amplifier, bias T

- Bias-T 5m cable

4 Results and Discussion

4a Diamond detectors’ CPS vs. reactor power – sensitivity, linearity

Integration time (?)

0 200 400 600 800 1000100

101

102

103

104

105

500 W 100 W 10 W 1 W 0.1 W 0.01 W

coun

ts/c

hann

el


100

101

102

103

104

105

coun

ts/c

hann

elADC channel number

Fig. X Diamond detectors spectra acquired with charge sensitive electronics while increasing reactor

power. [left] OPT-scCVD, [right] PIM-scCVD

104 105 106 107 108 109

10-1

100

101

102

103

diam

ond

dete

ctor

[cps

]


Equation y = a + b*xWeight No WeightingResidual Sum of Squares

0.00337

Pearson's r 0.99989Adj. R-Square 0.99973

Value Standard ErrorD1 Intercept -5.10035 0.04817D1 Slope 0.98325 0.00724

threshold = 200 ch

0.7%

104 105 106 107 108 10910-2

10-1

100

101

102

103

diam

ond

dete

ctor

[cps

]



5.1638E-4


Value Standard ErrorD Intercept -5.50928 0.01886D Slope 1.00538 0.00283

0.3%

OPT-scCVD – optical grade e6 single crystal CVD diamond, metalized with Al ~100nm, 2 mm in diameter

front contact, 17 microns thick

PIM-scCVD – electronic grade scCVD diamond grown in the Diamond Sensors Laboartory of CEA-Saclay.

Detector’s structure includes: HPHT substrate, p+ CVD diamond layer, which serves as a back contact 1-3

microns thick, intrinsic CVD layer >14 microns(?) thick

3c electronics

- 5m cable, Amptek, A250 charge sensitive amplifier, Ortec shaper, HV voltage unit, pocket M8000

ADC

- Cividec 50 Ohm amplifier, bias T

- Bias-T 5m cable

4 Results and Discussion

4a Diamond detectors’ CPS vs. reactor power – sensitivity, linearity

Integration time (?)

0 200 400 600 800 1000100

101

102

103

104

105

500 W 100 W 10 W 1 W 0.1 W 0.01 W

coun

ts/c

hann

el


100

101

102

103

104

105

coun

ts/c

hann

el

ADC channel number

Fig. X Diamond detectors spectra acquired with charge sensitive electronics while increasing reactor

power. [left] OPT-scCVD, [right] PIM-scCVD

104 105 106 107 108 109

10-1

100

101

102

103

diam

ond

dete

ctor

[cps

]reactor diagnostics [cps]


0.00337


Value Standard ErrorD1 Intercept -5.10035 0.04817D1 Slope 0.98325 0.00724

threshold = 200 ch

0.7%

104 105 106 107 108 10910-2

10-1

100

101

102

103

diam

ond

dete

ctor

[cps

]



5.1638E-4


Value Standard ErrorD Intercept -5.50928 0.01886D Slope 1.00538 0.00283

0.3%

gamma backgroundtypical spectra of fission products

varying reactor power (acq. 10min) linearity vs. reactor diagnostics

U-235 alpha 4.679 MeV

easy to optimise:

- U-235 deposition onto diamond - thinner membrane (RH, gamm/n) - larger surface, sandwiching (sens.)

First Applications


Thanks for your attention!


UV 337nm laser TCT Photovoltaic Mode (zero-bias)Electronic Properties

ΔE

- - -+ +

membrane50 Ohm

laser absorbtion

DSOQE ~ 10-5UV 337nm, 2.5 ns pulse ~100µW nitrogen laser, trigger

p-doped

0 5 10 15 200.0

0.1

0.2

0.3

0.4

0.5

0.6

sign

al a

mpl

itude

on

50 O

hm [V

]

time [ns]

TCT signals

laser power

OD filters

Claudio Verona Tor Vergata Univ. Rome

0.01%

25%

metalintrinsic

p-dopedHPHT


PIM Membrane ‘Dosimetry’First Application

Methyl Viologen chemical dosimeter PIM membrane ‘dosimeter’


Zero-Bias Compared to ‘Normal’ Operation (bias-T – 20V applied)First Application

-1.0x10-6 0.0 1.0x10-6 2.0x10-6 3.0x10-6

-1

0

1

2

3

4

5

-0.02

0.00

0.02

0.04

0.06

0.08

0.10

indu

ced

curr

ent [

A]

sign

al a

mpl

itude

on

50 O

hm[V

]

time [s]

-1.0x10-6 0.0 1.0x10-6 2.0x10-6 3.0x10-6-0.1

0.0

0.1

0.2

0.3

0.4

0.5

sign

al a

mpl

itude

on

50 O

hm [V

]

time [s]

0V -20V

-1.0x10-6 0.0 1.0x10-6 2.0x10-6 3.0x10-6

-1

0

1

2

3

4

5

sign

al a

mpl

itude

on

50 O

hm [V

]

time [s]

-20V 0V

1 µs e-pulse

Documents

Michal Pomorski - GSI · Michal Pomorski, CEA-LIST, Diamond Sensors Laboratory, ADAMAS 3rd, Trento 19/11/2014 Co-Authors Co-Authors (CEA Saclay): Christine Mer-Calfati Francois Foulon