1 Underground Gamma-ray Spectrometry in HADES Mikael Hult Institute for Reference Materials and Measurements (IRMM) Geel, Belgium

2 Personnel involved in ILIAS activities - status 1 st 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

3 The EU Institutions Court 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 RELEXENTRENV SANCO JRC ….... IHCP... RTD IRMMIPSC ….. IPTS ….... Directorates General: the “Commission services” JRC Institutes: European Parliament

4 Structure of the DG-JRC IRMM – Geel, Belgium - Institute for Reference Materials and Measurements Staff:  250 IE – Petten, The Netherlands - Institute for Energy Staff:  180 ITU – Karlsruhe, Germany - Institute for Transuranium elements Staff:  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 Studies Staff:  Institutes in 5 Member States Total staff: ~ 2200 people

5 Olen – Geel – Mol - Dessel

6 Canberra Semiconductor Umicore SCKCEN + VITO (+ HADES) 5 km IRMM BR1 (700 kW) + BR2 (10 MW)

7 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

8 L e MeV n U GELINA : the Geel Linear Accelerator Neutron measurements with very high energy resolution using time-of-flight technique

9 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

10 HADES = High Activity Disposal Experimental Site

11

12 Detectors 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 Ge-9 ? Well-type 2006?

Normalised counting rate (d -1 keV -1 kg -1 ) Ge Gamma-ray energy (keV) Gamma-ray background spectrum Felsenkeller 125 m w.e. HADES 500 m w.e. Gran Sasso 3800 m w.e. Gran Sasso 3800 m w.e Gran Sasso 3800 m w.e. ~14 cm lead ~ 8 cm Cu

14 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.

15 Ge-production (i) 1) Raw material: residue from e.g. Zn-ore with 3-5% Ge 2) Reduction of Ge-oxide 3) Zone-refinement repeat 4) Czochralski growth Measurements  Resistivity  Hall  DLTS Resistivity measurement Zn-plant Balen?

16 Ge-production (ii) Reduction of Ge-oxide Needs a powerful furnace. A bit difficult to put underground but possible Zone-refinement 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)

Bi ( 222 Rn-daughter) 60 Co 65 Zn  -energy: 1115 keV Binding E (Cu): 8.98 keV Normalised counting rate (d -1 keV -1 kg -1 ) Ge Gamma-ray energy (keV)

18 What is underground?

19 1 Depth (meter water equivalent) Attenuation of radiation in earth’s crust muons Secondary neutrons Neutrons produced in lead by muons Neutrons from fission and ( ,n) Intensity cm -2 s -1 HADES Source: Gerd Heusser

20 JET Low-level measurements – a growing field! Hiroshima Radiation Protection Safeguards Ref.measurements Neutrinos /  Neutrinos /  Isotopic fingerprints Isotopic fingerprints Tokai-mura Decay data Small samples High temporal resolution Benchmarking Fast measurements Radiopurity for detector construction 14 ISST Nova Gorica, 2005

21 Why is this a current issue? Development in germanium detector technology 14 ISST Nova Gorica, Year Figure of Merit (s 1/2 ) The first Ge(Li) 3 crystals in one cryostat The first HPGe Planar Coaxial FoM =

22 14 ISST Nova Gorica, 2005 Source: Physics World, January 2004, “Controlled Fusion: the Next Step” By Gia Tuong Hoang and Jean Jacquinot JET

23 Collaboration of European Low- 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.

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

25 CELLAR-actions Setting 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

Depth (m w.e.) Muon fluence rate (a. u.) Background counting rate (d -1 kg Ge ) HADES ASSE/UDO Gran Sasso Modane Low background - above ground Felsenkeller There is still work to do!

Depth (m w.e.) Muon fluence rate (a. u.) Background counting rate (d -1 kg Ge ) The futureGo even deeper!

28 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)