Laboratori NazionalidelGran Sasso ITALY

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The low background laboratory at the Gran Sasso National Laboratories

Dr. Matthias LaubensteinLaboratori Nazionali del Gran Sasso

ITALY

Synergies in Low Background Radiation TechniquesUniversity of MinnesotaMinneapolis MN, USA

July 25th, 2005

July 25th, 2005 SiLBRT - Minneapolis 2

Introduction

• Many fundamental experiments aim to detect very weak signals. They have to fight against background of different origin.– cosmic radiation– particles of nuclear decays– intrinsic natural radioactivity⇒ low background α and γ spectroscopy @

L.N.G.S.

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LNGS

In 1979 A. Zichichi makes a proposal to the Italian Parliament for building a large underground laboratory inside the highway tunnel underneath the Gran Sasso, at that time under construction.

In 1982 the Parliament approves theconstruction, then completed in 1987.

In 1989 the first underground experiment, MACRO, is starting data taking.

The EAS-TOP experiment, on Campo Imperatore, already started working from 1987 on.

The birth

QuickTime™ and aPhoto - JPEG decompressor

are needed to see this picture.


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Some very deep underground laboratories

CanfrancSpain

BoulbyUK Modane

France


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Underground laboratories

HALL C

HALL B

HALL A

Borexino

OPERA

LVD

ICARUS

CRESST2

CUORICINO

LBL-2

HDMS

GENIUS-TF

DAMAGerda

LBL-1

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LNGS and the ILIAS EU initiative

ILIAS=

Integrated Large Infrastructures forAstroparticle Science


ILIAS was proposed under the coordination and review of APPEC (AstroParticle Physics European Coordination)

ILIAS is an initiative supported by the EU VI Framework Programmewith the aim to support the EU Large infrastructures operating in the

astroparticle physics sector

France : Commissariat a l’Energie Atomique, CNRSItaly: Istituto Nazionale di Fisica Nucleare, Istituto di Fotonica e Nanotecnologie Trento,

European Gravitational Observatory

Germany: Max-Planck-Institut für Kernphysik Heidelberg, Technische Universität München, Max-Planck-Institut für Physik München, Eberhardt-Karls-Universität Tübingen

Spain: Zaragoza UniversityUK: Universities of Sheffield, Glasgow, and LondonCzech Rep.: Czech Technical Univ. in PragueDenmark: University of Southern Denmark Netherland: Leiden UniversityFinland: University of Jyväskylä Slovakia: Comelius University BratislavaGreece: Aristotle University of Thessaloniki

Participants

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The ILIAS project is based on three main groups of activities

• Networking activitiesaim: favour the contacts/collaborations among researchers working on

the same fields in different EU countriessupport: organisation of workshops, visits, specific activities

• Transnational Access activitiesaim : support access of EU researchers to major research infrastructuressupport: subsistence and travel costs for host researchers

costs of technical support for the hosting institution

• Joint research activitiesaim : support specific R&D activities conducted jointlysupport: travel costs

personnelequipment and consumables


Laboratoire Souterrainde Modane, France

Institute of UndergroundScience in Boulby mine,

UK

Laboratorio Subterraneode Canfranc, Spain

LSC

IUS

Laboratori Nazionali delGran Sasso, Italy

LNGS

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A1 : TARI-DUSLTransnational Access to the EU Deep Underground Science Laboratories

N2 : EUNet-DUSLEuropean Network of the Deep

Underground Science Laboratories

J1 : LBT-DUSLow Background Techniques for Deep

Underground Science

Activities of the Deep Underground Laboratories in ILIAS

Joint R&D for the improvement of the strengthening of the low background facilities and know-how of the UG labs

Coordination and networking to support the management of common issues relevant in the operation of the UG Labs

Activity

Support for the transnational access ofresearch teams to the EU underground labs with priority to researchers from less favoured countries


J1 : Low background techniques for deepUnderground science

MotivationsMotivations ::

Extremely low-level background techniques and instrumentation are an essential requirement for a number of topics in astroparticle physics, f.i.:

v Search for bb decayv Search for Dark matterv Detection of low-energy neutrinos (solar, geo)

Fundamental topics common to most experiments are:- Selection of radiopure materials- Techniques for shielding against environmental backgrounds- Purification techniques

This is the main motivation to carry on a Joint Research Activity onLow Background Techniques coordinated by the 4 UG Labs within ILIAS

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Key Key R&D R&D topicstopics::

v Development and strenthening of the ultra-low background facilitiesand instrumentation in the UG labs

v Measurement and monitoring of the background components in the underground Labs – Development of background simulation codes

v Application of low background techniques to interdisciplinary fields

v R&D on radiopurity of materials and purification techniques.

EUEU Support to Support to LNGS :LNGS :

v Personnel (2 post-docs + 1 technician)v Travel moneyv Contribution to equipment and consumables for selected specific activities


A1 : Transnational Access

The key objective of the Transnational Access is to offer free access to the

deep Underground labs for EU research teams to carry out short or medium-term

projects using the underground environment and facilities offered by the labs

projects are selected by a User Selection Panel (USP) which meets periodically

EUEU Support to Support to LNGS :LNGS :

v Travel and subsistence money for the host researchersv Contribution to management costs

LNGS was already supported for Transnational Access since December 2001Within contract HPRI-CT-2001-00149 (to be competed in December 2004)

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N2 : Network of the EU Deep Undergr. Labs

Objectives Objectives ::

• Scientific coordination and public communicationseveral specific activities ongoing (R. Antolini)

- open days at the underground labs- preparation of booklet on underground science for general

public- dedicated web pages

• Safety problems and accident preventionExchange of information, visits of experts, ….

• Service Improvement, coordination and extension of deep underground laboratories


Rock properties

• composition:

Ca 26 %, Si 1 %, Mg 9 %, O 51.5 %,C 12.5 %

<ρ> = (2.71 ± 0.05) g cm-3

<Z> = 11.4

<Z2/A> = 5.7

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Rock properties

radioactivity (in Bq kg-1):

100-20005-5040K

30-3004.5226Ra

80-5005238U

≈900.25-0.5232Th

Mt BlancGran Sasso


Characteristics

lat. 42o 27’ Nlong. 13o 34’ E

mean depth:3800 m.w.e.

min. depth:3000 m.w.e.

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Muons

muon fluence:≈ 1 µ/(m2⋅h), Eµ>1 TeV

(106 reduction with respect to surface)

LNGS


Neutrons

neutron flux:e.g. @ L.N.G.S.

fission and (α,n)Φth ≈ 3×10-6 cm-2 s-1

Φfc < 0.3×10-6 cm-2 s-1

(103 reduction)

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Low background counting laboratory

8 (+3) HPGe detectors working

1.9102%413GeMPI p-type

2.04×96%4×225GeMulti p-type

2.0120%465GeCris p-type

2.0113%518GePaolo p-type

1.996%414GsOr p-type

1.891%363GePV p-type

1.986%403GeMi p-type

2.056%235GeBer n-type

FWHM [keV]rel. efficiencyvolume [cm3]type


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Collaboration of European Low-LevelUnderground Laboratories

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University ofIceland

IAEA-MEL

ARCS

LNGS

IRMM

LSCE

VKTA

MPI-K

PTB


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.

Mission

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Partners:Partners:

(m w.e. = meter water equivalent, the height of water equivalent to that of the actual shielding material)

(~ 1750 m(~ 1750 m ≅≅ 4800 m w.e.4800 m w.e.))LSCE LSCE -- FranceFrance

(~ 1400 m(~ 1400 m ≅≅ 3800 m w.e.3800 m w.e.))LNGS LNGS -- ItalyItaly

(~ 925 m(~ 925 m ≅≅ 2100 m w.e.2100 m w.e.))PTB PTB -- GermanyGermany

(~ 225 m(~ 225 m ≅≅ 500 m w.e.500 m w.e.))IRMM IRMM -- EU EU -- BelgiumBelgium

(~ 165 m(~ 165 m ≅≅ 350 m w.e.350 m w.e.))University of IcelandUniversity of Iceland

(~ 50 m(~ 50 m ≅≅ 110 m w.e.110 m w.e.))VKTA VKTA -- GermanyGermany

(~ 14 m(~ 14 m ≅≅ 30 m w.e.30 m w.e.))IAEAIAEA--MEL MEL -- MonacoMonaco

(~ 8 m(~ 8 m ≅≅ 15 m w.e.15 m w.e.))MPIMPI--Heidelberg Heidelberg -- GermanyGermany

(above ground, (above ground, ~~ 3 m w.e.3 m w.e.))ARC Seibersdorf ARC Seibersdorf -- AustriaAustria

+ 1 associated partner (+ 1 associated partner (NPL NPL -- UKUK))


What is ULGS?

Ultra Low-level Gamma Spectrometry

i.e. low-level γ-spectrometry with additional background reduction by using active shields, material selection and/or underground laboratories

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Sensitivity

10-11ULGS + NAA

primordial parents

10-10 - 10-7ICP-MS (destructive)

primordial parents

10-8 - 10-7ULGS (non-destructive)

γ emitters

Detection limit for

U and Th [Bq/kg]

Method

1 Bq 238U/kg ≅ ≅ ≅ ≅ 81 x 10-9 g/g1 Bq 232Th/kg ≅ ≅ ≅ ≅ 246 x 10-9 g/g1 Bq 40K/kg ≅ ≅ ≅ ≅ 32 x 10-6 g/g


e.m. showers are only partially attenuated

Neutron thermalization produces photons through (n,γ) captureInteraction of high energy particles with shielding induces secondary background

γext

High energy muons are not stopped

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e.m. showers are attenuated

Neutron thermalization produces photons through (n,γ) captureInteraction of high energy particles with shielding induces secondary background

γext

high energy muons are reduced by overburden and/or active shield

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100

101

102

103

104

105

106N

orm

alis

ed c

ount

ing

rate

[d-1

kg-1

]

Depth [m w.e.]

0 300100 200 400 500

Muo

n fl

uenc

e ra

te [

a.u.

]

600 700

above ground

VKTA Rossendorf

JRC-IRMM

ARC Seibersdorf

MPI-K-HD

IAEA-MEL

active + passive shieldonly passive shield


Rn

high energy muons are reduced further deep underground(factor >10-6 reduction @ LSCE & LNGS)

Neutrons now induced from natural radioactivity ((α,n) & fission)(factor 10-3 reduction @ LNGS)

γext

γ's now from natural radioactivity inside shielding and detector components

gas radon becomes important

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BUT … !!!


10-1

100

101

102

103

104

105

106

Nor

mal

ised

cou

ntin

g ra

te [

d-1kg

-1]

10-2

Depth [m w.e.]

0 30001000 2000 4000 5000

Muo

n fl

uenc

e ra

te [

a.u.

]

LSCE

LNGS

PTBJRC-IRMM

VKTA Rossendorf

above ground

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10-1

100

101

102

103

104

105

106N

orm

alis

ed c

ount

ing

rate

[d-1

kg-1

]

10-2

Depth [m w.e.]

0 30001000 2000 4000 5000

Muo

n fl

uenc

e ra

te [

a.u.

]

199319961997

LNGS


10-4

10-3

10-2

10-1

100

101

102

103

Nor

mal

ised

cou

ntin

g ra

te [

d-1ke

V-1

kg-1

]

Energy [keV]0 1500500 1000 2000 2500 3000

above groundARC SeibersdorfVKTA RossendorfJRC-IRMMLNGS

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HPGe detectors

shielding:20 cm low activity lead (210Pb < 20 Bq kg-1)

5 cm OFHC copper

5 cm acrylic and Cd foil on the bottom

Rn-suppression:1 cm acrylic cover with continuous N2 flow

material selection:highly radiopure, (almost) no activation


plus continuous contribution of Ge intrinsic cosmogenics

ANG2 LNGS, no shieldHeidelberg Moscowplot from O. Chkvorets

β+

40K137Cs

ThU60Co

60Co

207Bi

0νββ

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HPGe detectors

0.24 ± 0.03< 0.06< 0.0730 ± 2GeMPI

0.88 ± 0.22< 0.130.29 ± 0.2277 ± 2GeCris

1461 keV583 keV352 keV40-2700 keV

1.8 ± 0.20.31 ± 0.161.1 ± 0.3222 ± 2GePaolo

4.2 ± 0.50.76 ± 0.352.0 ± 0.5442 ± 5GsOr

3.2 ± 0.41.8 ± 0.42.6 ± 0.7498 ± 5GePV

6.1 ± 0.81.4 ± 0.54.1 ± 1.0555 ± 7GeMi

total and peak background count rate [d-1 kg-1Ge] detector


GeMPIOperated at

LNGS

(3800 m w.e.)

G. HeusserB. Prokosch H. Neder

M. Laubenstein

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effective volume of sample chamber ~ 15 l(e.g. 125 kg Cu or 157 kg Pb)

High purity copper directly placed underground after electrolysis


OUTLOOK

further improvements possible:

- neutron shield- material selection improved- active shield- going deeper underground- storage of construction material underground- multisegmented crystals or multiple crystals- collaboration with producers

γext

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INFN LNGS, Assergi, ItalyA.Di Vacri, M. Junker, M. Laubenstein, C. Tomei, L. Pandola

JINR Dubna, RussiaS. Belogurov,V. Brudanin, V. Egorov, K. Gusev, S. Katulina,

A. Klimenko, O. Kochetov, I. Nemchenok, V. Sandukovsky, A. Smolnikov, J. Yurkowski, S. Vasiliev,

MPIK, Heidelberg, GermanyC. Bauer, O. Chkvorets, W. Hampel, G. Heusser, W.

Hofmann, J. Kiko, K.T. Knöpfle, P. Peiffer, S. Schönert, J. Schreiner, B. Schwingenheuer, H. Simgen, G. Zuzel

Univ. Köln, GermanyJ. Eberth, D. Weisshaar

Jagiellonian University, Krakow, PolandM.Wojcik

Univ. di Milano Bicocca e INFN, Milano, ItalyE. Bellotti, C. Cattadori

INR, Moscow, RussiaI. Barabanov, L. Bezrukov, A. Gangapshev, V. Gurentsov, V. Kusminov, E. Yanovich

ITEP Physics, Moscow, RussiaV.P. Bolotsky, E. Demidova, I.V. Kirpichnikov, A.A. Vasenko, V.N. Kornoukhov

Kurchatov Institute, Moscow, RussiaA.M. Bakalyarov, S.T. Belyaev, M.V. Chirchenko, G.Y. Grigoriev, L.V. Inzhechik, V.I. Lebedev, A.V. Tikhomirov, S.V. Zhukov

MPI Physik, München, GermanyI. Abt, M. Altmann, C. Bűttner. A. Caldwell, R. Kotthaus, X. Liu, H.-G. Moser, R.H. Richter

Univ. di Padova e INFN, Padova, ItalyA. Bettini, E. Farnea, C. Rossi Alvarez, C.A. Ur

Univ. Tübingen, GermanyM. Bauer, H. Clement, J. Jochum, S. Scholl, K. Rottler

71 physicists / 12 institutions / 4 countries Spokesperson: Stefan Schönert, MPIK Heidelberg

GERDAThe GERmanium Detector Array for the search

of neutrinoless double beta decay of 76Ge

53Ø 4.0 mØ 9.4 m

Ø 3.8 m

h c

a 5

m

8.3

m

2 x 10 cm Pb

1.5 mstainless steel

Vespel or similar

concrete

8x106

Ra-226

1x107

Th-228

9x107

K-40

radio-activity [µµµµBq/kg]

copper

<<<< 20

<<<< 26

<<<< 88

Ge

<<<< 1x10-3

<<<< 1x10-4

<<<< 1x10-2

10 cm Pb

water shield

instrumented with PMT‘s as cosmic veto

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ANG2 LNGS, no shieldHeidelberg Moscowplot from O. Chkvorets

2.039 MeV

envisioned levelfor Gerda

also next step for screening at nBq/kg level

exiting to see what comes up at this level

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Measurements

measurements of direct physics interest:

- 42Ar in natural liquid argon: 42Ar/40Ar ≤10-18

- double beta decay of 96Zr and 150Nd:

T½(96Zr) > 3 × 1019 a

T½(150Nd) > 1 × 1020 a

- Roman Pb (age > 2000 a): 210Pb <1.3 Bq/kg

− β-decay of 115In to 115Sn*: (3.73 ±0.98) × 1020 a


Cu of Norddeutsche Affinerie (Hamburg, Germany)

NOSV quality

99.9975% (1-4 ppm O2)

anodes 97-99 % + 2000 ppm O2

+...

Ni: % IN ORE < 1-2 ppm

Co: about 5 ppm < 1 ppm40K: 7.5 ±±±± 1.0 mBq/kg < 0.088 mBq/kg226Ra: 1.8 ±±±± 0.4 mBq/kg < 0.020 mBq/kg228Th: < 0.44 mBq/kg < 0.023 mBq/kg

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125 kg NOSV Cu for LENS measured with GeMPIG. Heusser

M. Laubenstein

< 19< 201.91 a228Th (Th)

455 ± 12044.5 d59Fe

53 ± 1883.79 d46Sc

110 ± 4015.97 d48V

primordial

< 16< 351600 a226Ra (U)

unexposedexposed (270 d)cosmogenic

< 88< 1201.277 × 109 a40K

215 ± 21312.15 d54Mn

activity [µBq/kg]halfliferadionuclide

< 102100 ± 1905.27 a60Co

1650 ± 9070.86 d58Co

1800 ± 400271.83 d57Co

230 ± 3077.31 d56Co

Cosmogenic* and primordial radioactivity concentrations in Cu


Development and strengthening of the ultra low-level background facilities (LNGS)

Ø Extension of the Low Level Laboratory at LNGSØ Development of new generation of HP-Ge detectors for Ultra-low level applicationsØ Set-up of ultra low-level scintillation counter systemsØ Ultra low-level gas counting (GNO low counting lab)

GNO Ultra low-level gas countingUltra low-level HPGe detector @ LNGS

Other activites

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Measurement and monitoring of the background componentsunderground

- Development of detectors for determination of neutron and gamma flux and spectrum

- Coordinated measurement and comparison of neutron and gamma spectra in all 4 UGlabs

- Set-up of Rn monitoring systems in air and water inside all 4 UG labs

New measurement and monitoringof n spectrum (INFN Pv)

γ-ray mapping in the LNGS


v Application of low backgroundtechniques to interdisciplinary fields

- low-level environmental radioactivity measurement and monitoring

- Radiodating laboratory

- Geophysics

v Radiopurity of materials andpurification techniques

- Set-up a database containing relevant information on radiopurity of materials commonly used for low background applications. Setting up an efficient database is not a trivialjob.

- Measurement of poorely known radiopurity ofmaterials with possible applcations within ultra-low background esperiments

- Cross-check of measuring methods available at the different labs.

W.Plastino, L. Kaihola

Laboratori NazionalidelGran Sasso ITALY

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