Organic Organic Scintillators for Scintillators for

NeutronsNeutronsAlberto QuarantaAlberto Quaranta

Laboratori Nazionali di Legnaro - Laboratori Nazionali di Legnaro - INFNINFN

University of Trento – Dept. University of Trento – Dept. Materials Engineering Ind. Materials Engineering Ind.

Technologies (DIMTI)Technologies (DIMTI)

Scintillators for thermal Scintillators for thermal neutronsneutrons

Scintillators for thermal neutrons are based on Scintillators for thermal neutrons are based on the detection of the reaction products between the detection of the reaction products between

neutrons and few nucleus which can be neutrons and few nucleus which can be dispersed in the scintillating matrix.dispersed in the scintillating matrix.

Scintillators for thermal Scintillators for thermal neutronsneutrons

Liquid scintillatorsLiquid scintillators: high : high efficiency, pulse shape for efficiency, pulse shape for n-n-

discrimination.discrimination.Toxic, corrosive, flammable, explosive...Toxic, corrosive, flammable, explosive...

Inorganic scintillatorsInorganic scintillators: high : high radiation hardnessradiation hardness

Cryst. growth technology, pressed Cryst. growth technology, pressed unhomogenous powders.unhomogenous powders.

Plastic scintillatorsPlastic scintillators: different : different shapes and volumesshapes and volumes

Low radiation resistance. New polymers Low radiation resistance. New polymers have to be studied. have to be studied.

Needs of new scintillators for Needs of new scintillators for neutronsneutrons

Neutron counting and Neutron counting and monitoring.monitoring.

Complex geometries and high Complex geometries and high volumesvolumes..

State of artState of art

Commercial plastic scintillators. BC-454/EJ-Commercial plastic scintillators. BC-454/EJ-245 (B).245 (B).

14 €/g for B containing.14 €/g for B containing.

Carborane as boron disperser in PSCarborane as boron disperser in PSVolatile, not always soluble and 100 €/g.Volatile, not always soluble and 100 €/g.

Plastic and microcrystal mixed Plastic and microcrystal mixed scintillators.scintillators.Unhomogeneous.Unhomogeneous.

Gd and B containing Gd and B containing silicone rubbers.silicone rubbers.

Studies are still at a Studies are still at a preliminar stage (Oak-Ridge).preliminar stage (Oak-Ridge).

ORIONEORIONE – – ORORganic scganic scIIntillators ntillators for for NENEutronsutrons

The aim of ORIONE experiment is develop The aim of ORIONE experiment is develop rubber scintillators for the detection of thermal rubber scintillators for the detection of thermal

neutrons.neutrons.

Selection of the Selection of the luminescent silicone luminescent silicone

rubber matrix.rubber matrix.

Selection of the luminescent Selection of the luminescent dye molecule converting in dye molecule converting in light the excited states of light the excited states of

the matrix.the matrix.Selection of a suitable Selection of a suitable

organic compound organic compound containing the reactive containing the reactive

nucleus.nucleus.

LNL – LNL – LNSLNS

Why silicone rubbers?Why silicone rubbers?

Good radiation hardness.Good radiation hardness.

Thermal stability (-55 up to 290 °C) and Thermal stability (-55 up to 290 °C) and workability (easy to cut and to handle).workability (easy to cut and to handle).

Fluorescence and refractive index can be Fluorescence and refractive index can be tailored by varying the amount of diphenyl tailored by varying the amount of diphenyl

groups.groups.

3-D cross linking can be attained to 3-D cross linking can be attained to improve the radiation hardness.improve the radiation hardness.

Dimethyl-diphenyl-polysiloxaneDimethyl-diphenyl-polysiloxane

Pre-irradiatio

n

After 3 Mrads

After 18 Mrads

Pre-irradiatio

n

Transmittance

Transmittance

PS irradiated PS irradiated in airin air

600 Ci 600 Ci 6060Co Co sourcesource

SR irradiated SR irradiated in airin air

600 Ci 600 Ci 6060Co Co sourcesource

M. Bowen et al. IEEE Trans. Nucl. Sci. 36 M. Bowen et al. IEEE Trans. Nucl. Sci. 36 (1989) 562(1989) 562

Suited dye moleculesSuited dye moleculesOverlap between dye absorption Overlap between dye absorption

spectrum and polymer fluorescence spectrum and polymer fluorescence spectrum.spectrum.

Good solubility in the polymer matrix.Good solubility in the polymer matrix.Good radiation hardness.Good radiation hardness.

250 300 350 400 450 5000.0

0.5

1.0 PPO emission band

PPO absorption bandSilicone emission

Nor

m. I

nten

sity

Wavelength (nm)

Silicone excitation

2,5 diphenyloxazole - 2,5 diphenyloxazole - PPOPPO

Preliminary testsPreliminary tests

300 400 500 6000.0

0.5

1.0

Nor

mal

ized

Yie

ld

Wavelength (nm)

2.0 MeV Photoluminescence X-rays 8 keV

Photoluminescence and radioluminescence Photoluminescence and radioluminescence measurements on silicone rubber doped with measurements on silicone rubber doped with only PPO show the dye emission band as the only PPO show the dye emission band as the

main luminescence feature.main luminescence feature.

Preliminary testsPreliminary tests

500 1000 1500 2000 25000

1000

2000

3000

Cou

nts

Channel

15% ph+0.5% PPO 15% ph+1% PPO NE102

241Am

Pulse height spectra Pulse height spectra show a higher light show a higher light

yield of silicone doped yield of silicone doped scintillator (1% PPO) scintillator (1% PPO)

with respect to NE102 with respect to NE102 under excitation with under excitation with

particles.particles.

1000 2000 3000 40000

200

400

60Co

Cou

nts

Channel

15% ph+0.1PO NE102 15% ph+1PO

0.0 0.4 0.8 1.2 1.6 2.00

200

400

600

800

1000

1200

1400

1600

Pea

k C

hann

el

% w/w PPO

15% DFS 25% DFS

2009 planned activity2009 planned activity

New organic compounds for New organic compounds for dispersing Gd and B in the silicone dispersing Gd and B in the silicone

polymer.polymer.

Gadolinium and Boron compounds Gadolinium and Boron compounds requirementsrequirements

Highly soluble in the siloxane fluids.Highly soluble in the siloxane fluids.

Inert to the cross-linking reaction and to the Inert to the cross-linking reaction and to the light yield.light yield.

Thermally resistant (up to 100°C, final Thermally resistant (up to 100°C, final annealing for the cross-linking annealing for the cross-linking completion).completion).

2009 planned activity2009 planned activity

Test on the effect of the compounds on the Test on the effect of the compounds on the scintillation yield and pulse shape.scintillation yield and pulse shape.

and and radiation sources and ion radiation sources and ion beams at LNL and LNS.beams at LNL and LNS.

Test on the radiation hardness of the Test on the radiation hardness of the silicone scintillators (crosslinking as an silicone scintillators (crosslinking as an

improvement).improvement). Scintillation degradation during ion Scintillation degradation during ion

irradiation. Formation of color centers after irradiation. Formation of color centers after exposure to the “Gamma Knife” exposure to the “Gamma Knife” 6060Co source Co source

at LNS (3 Gy/min).at LNS (3 Gy/min).

2009 planned activity2009 planned activity

First scintillation tests with First scintillation tests with neutrons.neutrons.

After the preparation of the neutron After the preparation of the neutron converter the first converter the first n n detection tests will be detection tests will be

performed at LNS.performed at LNS.

Graphite cylinder + lead Graphite cylinder + lead shield for gamma shield for gamma

background + PEHD for background + PEHD for moderating the neutrons.moderating the neutrons.

LNS neutron LNS neutron converterconverter

Planned activityPlanned activity

20102010

Full characterization for Full characterization for nn detection capabilities of the detection capabilities of the

produced scintillators.produced scintillators.

Pulse shape and height analyses for Pulse shape and height analyses for studying the capabilitiels for studying the capabilitiels for n-n-

discrimination.discrimination.

Nat. Resp.Nat. Resp. Alberto Quaranta Alberto Quaranta

LNL Resp.LNL Resp. Sara CarturanSara Carturan

Fabiana GramegnaFabiana Gramegna

Vladimir KravchukVladimir Kravchuk

Gianantonio Della Gianantonio Della MeaMea

Michele TonezzerMichele Tonezzer

Gabrio ValottoGabrio Valotto

Sandro SassiSandro Sassi

Mauro MasiolMauro Masiol

LNS Resp.LNS Resp. Maurizio ReMaurizio Re

Giacomo CuttoneGiacomo Cuttone

Gianluigi CosentinoGianluigi Cosentino

Alfio PappalardoAlfio Pappalardo

StaffStaff

Thank you for Thank you for your your

attentionattention