Lino Miramonti - 7 February 2006 - Honolulu Hawaii (USA) 1 Astroparticle Physics at Gran Sasso...

Lino Miramonti - 7 February 2006 - Honolulu Hawaii (USA) 1

Astroparticle Physics at

Gran Sasso Underground Laboratory:Borexino and geo-neutrino

Lino Miramonti – 7 Feb 2006 - Honolulu (Hawaii)


Particle physics

Astrophysics&

Cosmology

Astroparticlephysics

Astroparticle Physics

Typical studies of astroparticle physics are:

Neutrino Physics (Solar, Supernova, Atmospherics, Geoneutrinos, neutrinos from reactors and from accelerators, etc..)

Cosmic Ray Physics Rare Processes (double beta decay, proton decay etc..) Dark Matter (WIMP’s) Gravitational Waves Nuclear Physics (Cross section measurements of astrophysics

interest) …….

Typical studies of astroparticle physics are:

Neutrino Physics (Solar, Supernova, Atmospherics, Geoneutrinos, neutrinos from reactors and from accelerators, etc..)

Cosmic Ray Physics Rare Processes (double beta decay, proton decay etc..) Dark Matter (WIMP’s) Gravitational Waves Nuclear Physics (Cross section measurements of astrophysics

interest) …….

Very little cross sections and/or very rare processes of events means to locate detector apparatus to the shelter from cosmic radiation

UndergroundPhysics

Employs knowledges and techniques from particle physics in order to study cosmological and astrophysical aspects.

Detects particles coming from space for particle physics studies.


France Commissariat a l’Energie Atomique,

Centre National de la Recherche Scientifique

Italy Istituto Nazionale di Fisica Nucleare,

Istituto di Fotonica e Nanotecnologie Trento,

European Gravitational Observatory

Germany Max Planck Institut für Kernphysik, Technische

Universität München,

Max Planck Institut für Physik Muenchen, Eberhardt,

Karls Universität Tubingen

Spain Zaragoza University

UK Sheffield University,

Glasgow University,

London University

Czech Rep Czech Technical Univ. in Prague

Denmark University of Southern Denmark

Netherland Leiden University

Finland University of Jyväskylä

Slovakia Comenius University Bratislavia

Greece Aristot University of Thessaloniki

Integrated Large

Infrastructures

for

Astroparticle Science

ILIAS is an initiative supported by the

European Union with the aim to support the European large infrastructures operating in the astroparticle physics sector.


The ILIAS project is based on 3 groups of activitiesactivities:

• Networking Activities

(N2) Deep Underground science laboratories(N3) Direct dark matter detection(N4) Search on double beta decay(N5) Gravitational wave research(N6) Theoretical astroparticle physics

• Joint Research Activities (R&D Projects)

(JRA1JRA1) Low background techniques for Deep Underground ScienceLow background techniques for Deep Underground Science(JRA2) Double beta decay European observatory(JRA3) Study of thermal noise reduction in gravitational wave detectors

• Transnational Access Activities

(TA1) Access to the EU Deep Underground Laboratories


JRA1 JRA1 ((Joint Research Activities 1))

Low background techniques for deep underground sciences ( (LBT-DUSLLBT-DUSL))

ObjectivesObjectives::

Background identification and measurement (Background identification and measurement ( intrinsicintrinsic, , inducedinduced, , environmentalenvironmental))

Background rejection techniques (Background rejection techniques (shieldingshielding, , vetoesvetoes, , discriminationdiscrimination))

ObjectivesObjectives::

Background identification and measurement (Background identification and measurement ( intrinsicintrinsic, , inducedinduced, , environmentalenvironmental))

Background rejection techniques (Background rejection techniques (shieldingshielding, , vetoesvetoes, , discriminationdiscrimination))

A vast R&D programme on the improvement and implementation of ultra-low background techniques will be carried out cooperatively in the 5 European Underground Laboratories.

A vast R&D programme on the improvement and implementation of ultra-low background techniques will be carried out cooperatively in the 5 European Underground Laboratories.

Working packages

WP1: Measurements of the backgrounds in the underground labs

WP2: Implementation of background MC simulation codes

WP3: Ultra-low background techniques and facilities

WP4: Radiopurity of materials and purification techniques

Working packages

WP1: Measurements of the backgrounds in the underground labs

WP2: Implementation of background MC simulation codes

WP3: Ultra-low background techniques and facilities

WP4: Radiopurity of materials and purification techniques


http://www.lngs.infn.it/


LNGS permanent staff: 60 (physicists, technicians, administration)Scientists involved in LNGS experiments: 700 from 24 countries

LNGS


Operating Institution

Istituto Nazionale di Fisica Nucleare (INFN)

Location Gran Sasso Tunnel (Abruzzi, Italy)

Excavation 1987

Underground area 3 halls A B C (100m x 18m x 20m) + service tunnels

Depth 1400 m (3800 mwe)

Total volume 180000 m3

Surface > 6000 m2

3 main halls

A B C 100 x 18 m2 (h.20 m)


Muon Flux

1.1 μ m-2 h-1

Primordial Radionuclides

238U 6.8 ppm Rock (Hall A)

0.42 ppm Rock (Hall B)

0.66 ppm Rock (Hall C)

1.05 ppm Concrete All Halls

232Th 2.167 ppm Rock (Hall A)

0.062 ppm Rock (Hall B)

0.066 ppm Rock (Hall C)

0.656 ppm Concrete All Halls

K 160 ppm Rock

Neutron Flux

1.08 10-6 n cm-2 s-1 (0-0.05 eV)

1.84 10-6 n cm-2 s-1 (0.05 eV- 1 keV)

0.54 10-6 n cm-2 s-1 (1 keV-2.5 MeV)

0.32 10-6 n cm-2 s-1 (> 2.5 MeV)

Backgrounds & Facilities @ LNGS

Residual muon flux(6 order of magnitude lower than surface)

Coming from spontaneus fission (in particular from 238U) and (α,n) reaction on light elements in the rock

also µ-induced neutrons

Troublesome for anti-ν detection by Cowan-Reines reaction!

Rock of Hall A is 10 times more radioactive in 238U than Hall B and Hall C (and 30 times more radioactive in 232Th)


HPGe Hall(32 m2 floor)

FACILITY FOR LOW-LEVEL RADIOACTIVITY MEASUREMENTS

Present: 32 m2 on one floor in service tunnelFuture: 60 m2 distributed on three floors in hall A

Courtesy by Matthias.Laubenstein


Completed experiments

Atm ν, Monopoles MACRO (Streamer tubes + Liquid scintillators)Solar neutrinos GALLEX / GNO (~ 30 T Gallium radiochemical detector)ββ Heidelberg-Moscow (~ 11 kg enriched 76Ge detectors)

Mibeta (~ 7 kg Bolometers TeO2)Dark Matter DAMA (~ 100 kg NaI detectors)


Running experiments

ββ Cuoricino (~ 41 kg TeO2 crystals)Dark Matter CRESST (Sapphire cryodetector & CaWO4 crystals (phonons+scintillation))

LIBRA (~ 250 kg NaI crystals)HDMS / Genius-TF (Ge detector 73Ge enriched)

Supernova neutrinos LVD (Streamer tubes + Liquid scintillator)Nuclear astrophysics LUNA (Accelerator)


Under construction

CERN-GS beam ν OPERA (Emulsion)ICARUS (~ 600 T Liquid Argon)

Solar Neutrinos Borexino (~ 300 T Liquid scintillator)

Planned & proposed

ββ CUORE (~ 750 kg Te02)GERDA (76Ge)

Nuclear astrophysics LUNA-IIIGravitational waves LISA R&DDark matter Liquid Xe / Liquid Ar

http://www.lngs.infn.it/site/exppro/icarus/T600_photo_gallery/pages/Fig_b_half_module.htm


RADIOCHEMICALIntegrated in energy and time

CHERENKOVLess than 0.01% of the solar neutrino flux is been measured in real time.The main goal of Borexino is the

measurement in real time of the low energy component of solar neutrinos.

The main goal of Borexino is the measurement in real time of the low energy component of solar neutrinos.


Borexino Collaboration

– Italy (INFN & Universiy of Milano and Genova, Perugia Univ., LNGS)

– USA (Princeton Univ., Virginia Tech.)

– Russia (RRC KI, JINR, INP MSU, INP St. Petersburg)

– Germany (Hiedelberg MPI, Munich Technical University)

– France (College de France)

– Hungary (Research Institute for Particle & Nuclear Physics)

– Poland (Institute of Physics, Jaegollian University, Cracow)


BOREXINO: subsystemsScintillator purification systems:Water extractionVacuum distillationSilicagel adsorption

DI Water plant

Storage tanks: 300tons of PC

Borexino detector

Control roomCounting room

CTF


Core of the detector: 300 tons of liquid scintillator (PC+PPO) contained in a nylon vessel of 8.5 m diameter. The thickness of nylon is 125 µm.

1st shield: 1000 tons of ultra-pure buffer liquid (pure PC) contained in a stainless steel sphere of 13.7 m diameter (SSS).

2200 photomultiplier tubes pointing towards the center to view the light emitted by the scintillator.

2nd shield: 2400 tons of ultra-pure water contained in a cylindrical dome.

200 photomultiplier tubes mounted on the SSS pointing outwards to detect Cerenkov light emitted in the water by muons.


eLieBe 77

Eν = 862 keV (monochromatic)

ΦSSM = 4.8 · 109 ν s-1 cm2

e

xRecoil nuclear energy of the e-

expected rate (LMA hypothesis) is 35 counts/day in the 250-800 keV energy range

)1(10 244 MeVatcm

ee xx

Elastic Scattering


18 m


Cleen Room (on top of the Water Tank) for the insertions of lasers and sources for calibrations.


100 PMTs

4 tons of scintillator

4.5m thickness of water shield

Muon-veto detector

100 PMTs

4 tons of scintillator

4.5m thickness of water shield

Muon-veto detector

CTF is a prototype of Borexino. Its main goal was to verify the capability to reach the very low-levels of contamination needed for Borexino


The CTF as a tool for tuning the The CTF as a tool for tuning the apparatus before fillingapparatus before filling

In this moment we use the CTF in orderIn this moment we use the CTF in order: To asses the performances of the different BOREXINO sub-systems.

To test the 14C content in the PC

To test the efficiency of the purification methods (Water extraction, Vacuum distillation, Silicagel adsorption)

To test the cleanliness of the apparatus


1. Natural radioactivity

2. Muon Induced reactions

3. Cosmogenic induced isotopes

4. 14C

5. Air contaminants: 222Rn, 85Kr, 39Ar

1. Natural radioactivity

2. Muon Induced reactions

3. Cosmogenic induced isotopes

4. 14C

5. Air contaminants: 222Rn, 85Kr, 39Ar


Primordial radioactivity: ( about 20 radioisotopes with half-life > Earth life)

between them:238U and 232Th (α and β emitters)40K (β emitter with end-point = 1.3 MeV)

• Selection of materials

• Surface treatment to avoid dust and particulate

• Purification: • Water extraction, • Vacuum distillation, • Ultra filtration• Nitrogen sparging

• Selection of materials

• Surface treatment to avoid dust and particulate

• Purification: • Water extraction, • Vacuum distillation, • Ultra filtration• Nitrogen sparging

• Alpha/Beta Discrimination

• Delayed Coincidence

• Alpha/Beta Discrimination

• Delayed Coincidence

Natural radioactivity


Typical Conc. Borexino level

238U, 232Th ~ 1ppm in dust

~ 1ppb stainless steel

~ 1ppt IV nylon

~ 10-16g/g (PC)

~ 10-14g/g (water)

Knat ~ 1ppm in dust < 10-13g/g (PC)

Purification of the Scintillator (with US Skids):

•Water extraction: Impurity with high solubility in aqueous phase such as K and heavy metals in U Th chains. •Vacuum distillation: Low volatility components such as metals and dust particles.

•Ultra filtration: Particle dust.

•Nitrogen stripping: Nobles gases.


The excitation of the scintillator depends on many factors including the energy loss density – a large dE/dx enhances the slow component of the decay curve

The ratio tail over total is expected to be greater for alpha than for electrons

Tail/Total charge ratio

An efficiency for alpha identification of ~ 97% at 751 keV with an associated beta misidentification of ~ 2.5%.

At low energies (300-600 keV) the alpha I dentification efficiency range from 90 to 97 % with an associated beta misidentification of ~ 10%.


222Rn

218Po

214Pb 214Bi 214Po

210Pb

T=163 µs

α=5.49 MeV

α=6.02 MeV

α=7.69 MeV

210Bi 210Po

210Pb

α=5.30 MeV


220Rn

216Po

212Pb 212Bi 212Po

208Pb

T=19.8 m

T=0.3 µs

208Tl

224Ra

α=5.68 MeV

α=6.29 MeV

α=6.792 MeV

α=8.79 MeVα=6.04 MeV


Muon Induced reactions

At LNGS we have 1.1 µ m2 h-1 with a <Eµ> = 320 GeV

11Be τ = 13.8 s β-

7Be τ = 53.3 d β- EC

11C τ = 20.4 m β- EC

10C τ = 19.3 s β- EC

These elements having a τ > 1 s is not possible to tag them

Interacting with 12C of the organic scintillator they give:

A muon-veto system (The outer water shielding serves at the same time as water Cerenkov detector for

atmospheric muons) reduce this number by a factor 5000-10000

Ultrarelativistic µ can produce n which after been captured by p give a 2.2 MeV γ ray:

)2.2( MeVdpn


Cosmogenic induced isotopes

XBeCn 712

During transportation, pseudocumene is exposed to cosmic neutrons.Pseudocumene is produced in Sardinia and the voyage to LNGS take about one day.During transportation cosmic neutrons interact with 12C producing 7Be:

Be-7 decays by electron capture to Li-7 and emits (with a 10.52% branching fraction) a 478 keV gamma. This line is a potential background in the Borexino neutrino window.

Theoretical sea-level Cosmic Ray Flux(Latitude New York City ≈ LNGS)

7Be is efficiently removed by distillation!


14C

Typical Conc. Borexino level

14C/ 12C < 10-12 14C/ 12C ~ 10-18

The 14C content depend on the site of extraction. There is no possibility to eliminate this radionuclide, the only thing we can do, is to test, in CTF, samples of pseudocumene before to transport it to LNGS.

Our threshold (at 250 keV) is due to the 14C!

The reactions expected to contribute the most to 14C production in deep underground geological formations are:


Air contaminants: 222Rn, 85Kr, 39Ar Regular N2

High Purity N2

LAK (Low Ar/Kr content) N2

N2 used to sparge scintillator

Origin Typical Conc. (in air)

Borexino

level

222Rn 238U chain 10-100 Bq/m3 ~ 70 Bq/m3 in PC

85KrAnthropogenic origin (nuclear fue reprocessing)

1 Bq/m³ 0.16 0.16 Bq/mBq/m33 in N in N22

39Ar Cosmogenic production 11 mBq/m³ 0.5 0.5 Bq/mBq/m33 in N in N22

85Krβ emitter: Emax = 687 keV (Eγ = 514 keV)Half-life: 10.8 years

39Arβ emitter: Emax = 565 keV (no gamma)Half-life: 269 years

To reduce the effect of emanation we used only electroplisched stainless steel, applied orbital weldings .


Liquid Nitrogen (commercial quality 4.0, i.e. 99,99%) is delivered with a truck and stored on site in three tanks of 6 m³. The tanks can be refilled without interrupting the nitrogen supply.

•For Standard Purity N2 the liquid nitrogen is simply evaporated. The gas passes through a heat exchanger to keep it at constant temperature of ca. 15°C. The level of 222Rn is usually in the range of 0.1 – 0.2 mBq/m³ (STP).

•For the High Purity N2 the liquid nitrogen passes through a cryogenic adsorption trap ("LTA" = Low Temperature Absorber), filled with 11.5 liters of activated carbon. (We use CarboAct F3/F4, which was found to be very low in 226Ra (less than 0,3 mBq/kg)). For the evaporation we use an electrical evaporator with only low surface. The level of 222Rn is usually is below 1 µBq/m³ (STP). The output can be up to 100 m³/h.


Deionization Unit

Reverse Osmisis

Nitrogen StrippingUltra Filters


Schematic of the scintillator purification system for CTF. The scintillator is either water extracted, or vacuum distilled then filtered and stripped with nitrogen before being returned to the scintillator containment vessel.

The purification system was constructed entirely of electropolished stainless steel, quartz and teflon


Installation of the US Skids

Lino Miramonti - 7 February 2006 - Honolulu Hawaii (USA) 53Installation of the US Skids


Earth emits a tiny heat flux with an average value of

ΦH ~ 60 mW/m2

Integrating over the Earth surface:

HE ~ 30 TW

Giving constrain on the heat generation within the Earth.

Detecting antineutrino emitted by the

decay of radioactive isotopes

It is possible to study the radiochemical composition of the Earth


K)of% 0.0118K( nat40

gBq40

gBq232

gBq238

30K

4000Th

12300U

K)of% 0.0118K( nat40

gBq40

gBq232

gBq238

30K

4000Th

12300U

(ε is the present natural isotopic abundance)

(11%) MeV1.51e

νAreK

(89%) MeV1.32e

νeCaK

MeV42.8e

ν44e6αPbTh

MeV51.7e

ν66e8αPbU

4040

4040

-208232

-206238

238U 232Th 40K

g

W103.6ε(K)

g

W102.7ε(Th)

g

W109.5ε(U)

21

8-

8-

Heat

sgK

sgK

sgTh

sgU

Neutrinos

e

e

e

e

e

e

e

e

3.3)(

27)(

106.1)(

104.7)(

4

4

The 235U chain contribution can be neglected

2ln2

1A

N A

g

W109.8

J

MeV101.6MeV51.7

g

Bq12300 813-

sge

e

4104.76g

Bq12300

Heat

:ratio fixeda haselement Each


The best method to detect electron antineutrino is the classic Cowan Reines reaction of capture by proton in a liquid scintillator:

The electron antineutrino tag is made possible by a delayed coincidence of the e+ and by a 2.2 MeV γ-ray emitted by capture of the neutron on a proton after a delay of ~ 200 µs

enpe

)8.1(2)()( 2 MeVQcmQEeE ee


238U and 232Th chains have 4 β with E > 1.8 MeV : end.point

[Th-chain] 228Ac < 2.08 MeV

[Th-chain] 212Bi < 2.25 MeV

[U-chain] 234Pa < 2.29 MeV

[U-chain] 214Bi < 3.27 MeVAnti-neutrino from 40K are under threshold!

The terrestrial antineutrino spectrum above 1.8 MeV has a “2-component” shape.

high energy component coming solely from U chain andlow energy component coming with contributions from U + Th chains

This signature allows individual assay of U and Th abundance in the Earth


13C(α,n)16O

Reactors

Nature vol 436 july 20 2005Experimental investigation of geologicallyproduced antineutrinos with KamLAND

α’s are produced by 210Po that created by the 210Pb (τ = 22.3 y)

210Pb 210Bi 210Po

210Pb

α=5.30 MeV

KamLAND


Borexino is located in the

Gran Sasso underground laboratory (LNGS)

in the center of Italy: 42°N 14°E

Calculated anti-νe flux at the Gran Sasso Laboratory

(106 cm-2 s-1)

U Th Total (U+Th) Reactor BKG

Crust Mantle Crust Mantle

3.3 0.95 3.0 0.77 8.0 0.39

Data from the International Nuclear

Safety Center (http://www.insc.anl.gov)

Background from nuclear

Reactors

Earth data from F. Mantovani et al., Phys. Rev. D 69 (2004) 013001

No working nuclear plants in Italy

The nearest are at about 700 km


210Pb concentration measured in the Counting Test Facility

20 /Bq ton

Background from Po-210 13 16( , )C n O

• 210Pb related background negligible

• Only significant source of background are nuclear reactors

• Accidental rate also negligible (< 10% of reactors background)


The number expected events in Borexino are:

The background will be:

yr

events6

yr

events19

Predicted accuracy of about 30%

in 5 years of data taking

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