1

Underground Gamma-ray Spectrometry in HADES

Mikael Hult

Institute for Reference Materials and Measurements (IRMM)Geel, Belgium

http://www.irmm.jrc.be http://www.jrc.cec.eu.int

2

Personnel involved in ILIAS activities - status 1st half of 2005

• Uwe Wätjen (D), Sector Head Radionuclide Metrology, in EUROMET Technical Committee Ionising Radiation, CCRI Section II

• Mikael Hult (S), Group leader low-level measurements, co-ordinator of CELLAR,

• Gerd Marissens (B), Chief technician

• Joël Gasparro (F), Post doc. Fellow

• Werner Preusse (D), Visiting scientist

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The EU InstitutionsCourt of Auditors

JRC can apply for funding from DG RTD like any other institution. The only restriction is that JRC persons are not allowed to co-ordinate indirect actions

The Council of Ministers

Committee of the Regions

Court of Justice

The European Commission(the ‘College’ of Commissioners)

Economic and Social Committee

SG RELEX ENTR ENV SANCO JRC…. ...

IHCP

... ... ... RTD

IRMMIPSC …..IPTS

…. ......

Directorates General: the “Commission services”

JRC Institutes:

European Parliament

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Structure of the DG-JRC

IRMM – Geel, Belgium- Institute for Reference Materials and MeasurementsStaff: 250

IE – Petten, The Netherlands- Institute for EnergyStaff: 180

ITU – Karlsruhe, Germany - Institute for Transuranium elementsStaff: 250

IPSC - IHCP - IES – Ispra, Italy - Institute for the Protection and the Security of the Citizen - Institute for Health and Consumer Protection - Institute for Environment and Sustainability Staff: 350, 250, 370

IPTS – Seville, Spain- Institute for Prospective Technological StudiesStaff: 100

7 Institutes in 5 Member States

Total staff: ~ 2200 people

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Olen – Geel – Mol - Dessel

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Canberra Semiconductor

Umicore

SCK•CEN + VITO (+ HADES)

5 km

IRMM

BR1 (700 kW) + BR2 (10 MW)

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Nearby facilities

• Canberra Semiconductor – for HPGe detector assemblies

• Umicore – for Ge crystal growth

• IRMM – for radioactivity measurements (low-level or high accuracy)

• IRMM – other facilities: LINAC, Van de Graaff, reference facilities in analytical chemistry etc.

• SCK – HADES, 2 research reactors and analytical facilities

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Le-

150 MeV

n

U

GELINA : the Geel Linear Accelerator

Neutron measurements with very high energy resolution using time-of-flight technique

22

T

Lmv

2

1E

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IRMM core competences & research areas

Core competences• Food analysis & bio-analysis• Reference materials• Chemical/isotopic reference measurements• Radionuclide metrology• Neutron physics (LINAC, VdG)

Applied in the fields of• Food safety and quality• Biotechnology and health• Environment• Nuclear safeguards• Nuclear safety• Nuclear waste treatment

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HADES = High Activity Disposal Experimental SiteHADES = High Activity Disposal Experimental Site

Overburden:~ 175 m sand~ 50 m clay

Location ofIRMM’s ULGS

setupFirst shaftSecond shaftConstructed 1999

Test driftConnecting galleryConstructed 2003

PRACLAY gallery

223

m

84 m67 m

39 m

{

Overburden:~ 175 m sand~ 50 m clay

Location ofIRMM’s ULGS

setupFirst shaftSecond shaftConstructed 1999

Test driftConnecting galleryConstructed 2003

PRACLAY gallery

223

m

84 m67 m

39 m

{

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Detectors in HADESDetectors in HADES

• Ge-8 is ordered (high resolution – low background at low energies)

• Ge-4 and Ge-7 will be placed in the same shield to form a sandwich detector

Detector name Manufacturer Crystal type

Relative efficiency (%)

Year installed

Ge-2 Eurisys n-type semiplanar 8 1995Ge-3 Eurisys p-type coaxial 60 1997Ge-4 Canberra p-type coaxial (XTRa) 106 2000Ge-5 Canberra p-type planar (BEGe) 50 2001

Ge-6Canberra /

Ortec p-type coaxial 80 2004

Ge-7 Canberrap-type coaxial (XTRa)

with inverted head 80 2005Ge-8 Canberra p-type planar (BEGe) 38 2006Ge-9 ? Well-type 2006?

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-5

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-1

-3

Nor

mal

ised

cou

ntin

g ra

te (

d-1 k

eV-1 k

g-1

)G

e

Gamma-ray energy (keV)500 20001000 1500

Gamma-ray background spectrum

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Felsenkeller 125 m w.e.Felsenkeller 125 m w.e.

HADES 500 m w.e.HADES 500 m w.e.

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Gran Sasso 3800 m w.e.Gran Sasso 3800 m w.e.0

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Gran Sasso 3800 m w.eGran Sasso 3800 m w.e.

~14 cm lead

~ 8 cm Cu

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General comments on materials

Variability between batches

If you want to have a ULB HPGe you need to select the materials yourself and have the detector tested in a reputable deep underground laboratory very near to a manufacturer.

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Ge-production (i)

1) Raw material: residue from e.g. Zn-ore with 3-5% Ge

2) Reduction of Ge-oxide

3) Zone-refinement

repeat4) Czochralski growth

Measurements

Resistivity

Hall

DLTS

Resistivity measurement

Zn-plant Balen?

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Ge-production (ii)Reduction of Ge-oxide

Needs a powerful furnace. A bit difficult to put underground but possible

Zone-refinement

12-13 days work (24/24)=> > 1 months without shift work

Relatively easy to put underground (“low power”, some gas)

Czochralski growth

2-3 days

Relatively easy to place underground

(small “low power”, some gas)

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0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1080 1100 1120 1140 1160 1180 1200

214Bi(222Rn-daughter) 60Co

65Zn

-energy: 1115 keV

Binding E (Cu): 8.98 keV

Nor

mal

ised

cou

ntin

g ra

te (

d-1 k

eV-1 k

g-1

)G

e

Gamma-ray energy (keV)

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Depth (m w.e.)

Idiom Characteristics

< 10 Not underground or

above ground

The soft component (e, e+, photons) is strongly reduced but still plays a part.

Very little reduction of muon flux and neutron induced by muons. Muon shields are useful.

10 – 100 Shallow underground

The soft component of the cosmic ray has vanished. The muon flux is reduced a factor of 5-50, but Muon shields are useful. There is still a significant flux of neutrons produced by muons (reduction

of factor 2-10). The activation of crystal and shield are still important factors.

100 – 1000 Semi deep

underground

Cosmogenic activation can be neglected. A slight improvement can be obtained by discriminating against muons. The neutron flux is dominated by (,n) sources

> 1000 Deep underground

The influence of the cosmic rays can be neglected. The only source for neutrons are (,n) reactions.

What is underground?

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Attenuation of radiation by depth

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

0.01 0.1 1 10 100 1000

Depth (meter water equivalent)

Inte

nsi

ty (

par

ticl

kes/

cm2 /s

)

1

Depth (meter water equivalent)0.1 10 100 1000

10-4

10-5

10-3

10-2

10-1Attenuation of radiation in earth’s crust

muons

Secondary neutrons

Neutrons produced in lead by muons

Neutrons from fission and (,n)

Inte

nsi

ty c

m-2 s

-1

HADES

Source: Gerd Heusser

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JETJET

Low-level measurements – a growing field!

HADES 1999-2002

(FP5)

210Pb in lung cells3%

Various7%

Maintenance and new installations

7%

60Co in German steel1%

60Co in steel from Hiroshima

3%

Nuclear safeguards3%

BOREXINO5%

Zn in GaAs2%

Reference materials4%

26Al intercomparison3%

Neutron data3%

210Pb and Th in human bones15%

Radioprotection 14%

JCO accident11%

Bkg+calibration19%

HiroshimaHiroshimaRadiation ProtectionRadiation ProtectionSafeguardsSafeguards

Ref.measurementsRef.measurements

Neutrinos / Neutrinos /

Isotopic fingerprintsIsotopic fingerprintsTokai-muraTokai-mura

Decay dataDecay data

Small samplesSmall samples

High temporal High temporal resolutionresolution

BenchmarkingBenchmarking

Fast measurementsFast measurements

Radiopurity for detector Radiopurity for detector constructionconstruction

14 ISST Nova Gorica, 2005

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Why is this a current issue?

Development in germanium detector technology

14 ISST Nova Gorica, 2005

1965 1970 1975 1980 1985 1990 1995 2000 2005

10-1

100

101

102

103

104

Year

Fig

ure

of M

erit

(s1

/2)

The first Ge(Li)

3 crystals in one cryostat

The first HPGePlanar

Coaxial

)()(

)(

EBER

E

FoM = )()(

)(

EBER

E

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14 ISST Nova Gorica, 2005

Source: Physics World, January 2004, “Controlled Fusion: the Next Step”

By Gia Tuong Hoang and Jean Jacquinot

JET

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Collaboration of European Low-Collaboration of European Low-level underground LAboRatories level underground LAboRatories

Mission: Mission: To promote higher quality and sensitivity in ultra low-level radioactivity measurements for the improvement of crisis management, environment, health and consumer protection standards of Europe.

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• LSCE - France LSCE - France (-2200 m)(-2200 m) • LNGS - Italy LNGS - Italy (-1700 m)(-1700 m) • PTB - Germany PTB - Germany (-925 m => -415 m)(-925 m => -415 m) • IRMM - EU IRMM - EU (-225 m) (-225 m) • University of Iceland University of Iceland (-165 m)(-165 m) • VKTA - Germany VKTA - Germany (-50 m)(-50 m)• IAEA-MEL - MonacoIAEA-MEL - Monaco • MPI-Heidelberg - Germany MPI-Heidelberg - Germany (-10 m)(-10 m)• ARC-Seibersdorf – Austria (- 2 m)ARC-Seibersdorf – Austria (- 2 m) + associated partners+ associated partners

CELLAR-PartnersCELLAR-Partners

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CELLAR-actionsSetting up of a programme (in close contact with ICRM LLWG) involving actions like:

• Joint purchase and underground storage of electrolytic copper. Testing of equipment.

• ‘Travelling detector’ - study of background at different laboratories using one detector to better optimise construction of detectors made from Ge, NaI and CsI

• Intercomparisons of low-levels of activity (crisis management and international equivalence)

• Joint publications describing state of the art, applications areas and future development

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0 1000 2000 3000 4000 500010-2

10-1

100

101

102

103

104

105

106

Depth (m w.e.)

Mu

on

flue

nce

ra

te (

a. u

.)

Ba

ckg

rou

nd

cou

ntin

g r

ate

(d-1

kg G

e)

-1

HADESASSE/UDO

Gran Sasso Modane

Low background - above ground

Felsenkeller

There is still work to do!

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0 1000 2000 3000 4000 500010-2

10-1

100

101

102

103

104

105

106

Depth (m w.e.)

Mu

on

flue

nce

ra

te (

a. u

.)

Ba

ckg

rou

nd

cou

ntin

g r

ate

(d-1

kg G

e)

-1

The future Go even deeper!

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Will some wealth from HADES reach ILIAS?

YES -If we can do like only Heracles

succeeded before ........... to take Cerberus for a walk

(= to manage to fulfil the necessary EC formalities)