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Astroparticle Physics at Gran Sasso Underground Laboratory: Borexino and geo-neutrino. Lino Miramonti – 7 Feb 2006 - Honolulu (Hawaii). Astroparticle Physics. Astrophysics & Cosmology. Particle physics. Astroparticle physics.

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slide1

Astroparticle Physics at Gran Sasso Underground Laboratory:

Borexino and geo-neutrino

Lino Miramonti – 7 Feb 2006 - Honolulu (Hawaii)

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

slide2

Astroparticle

Physics

Astrophysics

&

Cosmology

Particle

physics

Astroparticle

physics

  • Employs knowledges and techniques from particle physics in order to study cosmological and astrophysical aspects.
  • Detects particles coming from space for particle physics studies.
  • 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

Underground

Physics

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

slide3

Underground

Laboratories

in Europe

Pyhäsalmi

Boulby

Frejus

Canfranc

Gran Sasso

slide4

ILIAS

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.

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

slide5

The ILIAS project is based on 3 groups of activities:

  • 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)
    • (JRA1) Low 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

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

slide6

JRA1 (Joint Research Activities 1)

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

  • Objectives:
    • Background identification and measurement (intrinsic, induced, environmental)
    • Background rejection techniques (shielding, vetoes, discrimination)

Working packagesWP1: Measurements of the backgrounds in the underground labsWP2: Implementation of background MC simulation codesWP3: Ultra-low background techniques and facilitiesWP4: Radiopurity of materials and purification techniques

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.

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

slide7

LNGS - Laboratori Nazionali del

Gran Sasso

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

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

slide8

LNGS permanent staff: 60 (physicists, technicians, administration)

Scientists involved in LNGS experiments: 700 from 24 countries

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

slide9

3 main halls

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

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

slide10

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)

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

slide11

FACILITY FOR LOW-LEVEL RADIOACTIVITY MEASUREMENTS

Present: 32 m2 on one floor in service tunnel

Future: 60 m2 distributed on three floors in hall A

HPGe Hall

(32 m2 floor)

Courtesy by Matthias.Laubenstein

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

slide12

Experiments @ LNGS (Gran Sasso)

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)

MI-Beta

Macro

bb H-M

Gallex - GNO

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

slide13

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)

LUNA

LIBRA

HDMS

LVD

Cuoricino

CRESST

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

slide14

Under construction

CERN-GS beam ν OPERA (Emulsion)

ICARUS (~ 600 T Liquid Argon)

Solar Neutrinos Borexino (~ 300 T Liquid scintillator)

Borexino

Planned & proposed

ββ CUORE (~ 750 kg Te02)

GERDA (76Ge)

Nuclear astrophysics LUNA-III

Gravitational waves LISA R&D

Dark matter Liquid Xe / Liquid Ar

OPERA

ICARUS

CNGS

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

slide15

Borexino

CHERENKOV

Less than 0.01% of the solar neutrino flux is been measured in real time.

RADIOCHEMICAL

Integrated in energy and time

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

pp cycle

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

borexino collaboration
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)

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

borexino subsystems
BOREXINO: subsystems
  • Scintillator purification systems:
  • Water extraction
  • Vacuum distillation
  • Silicagel adsorption

Borexino detector

Storage tanks: 300tons of PC

Control room

Counting room

CTF

DI Water plant

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

slide18

Borexino

design

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.

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

slide19

Eν = 862 keV (monochromatic)

ΦSSM = 4.8· 109 ν s-1 cm2

Recoil nuclear energy of the e-

Elastic Scattering

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

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

slide20

Status of Borexino

The detctor is in this moment in commissioning

We expect to start data-taking november 2006

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

slide21

Experimental Hall C

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

slide22

External dome

18 m

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

slide23

Stainless Steel Sphere (SSS)

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

slide24

PMTs ready to be mounted

Clean Room

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

slide25

Borexino inner detector

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

slide26

Optical fiber istallation

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

slide27

Borexino inner detector

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

slide28

Nylon vessels

(Princeton Univ.)

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

slide29

Nylon vessels installation

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

slide30

Nylon vessels installation

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

slide31

Nylon vessels installed and inflated

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

slide32

Cables installation

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

slide33

Counting

Room

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

slide34

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

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

slide35

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

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

slide36

Counting Test Facility (CTF)

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

100 PMTs

4 tons of scintillator

4.5m thickness of water shield

Muon-veto detector

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

slide37

Internal view of CTF

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

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

In 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

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

slide39

Backgrounds we have to fight

Natural radioactivity

Muon Induced reactions

Cosmogenic induced isotopes

14C

Air contaminants: 222Rn, 85Kr, 39Ar

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

slide40

Natural radioactivity

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

Hardware

  • Alpha/Beta Discrimination
  • Delayed Coincidence

Software

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

slide41

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.

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

slide42

alpha/beta discrimination

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

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%.

Tail/Total charge ratio

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

slide43

Delayed Coincidence in U238 chain

222Rn

α=5.49 MeV

218Po

α=6.02 MeV

214Pb

214Bi

214Po

α=7.69 MeV

T=163 µs

210Pb

210Bi

210Po

α=5.30 MeV

210Pb

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

slide44

Delayed Coincidence in Th232 chain

224Ra

α=5.68 MeV

220Rn

α=6.29 MeV

216Po

α=6.792 MeV

T=19.8 m

212Pb

212Bi

212Po

α=6.04 MeV

α=8.79 MeV

T=0.3 µs

208Tl

208Pb

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

slide45

Muon Induced reactions

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

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

Interacting with 12C of the organic scintillator they give:

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

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

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

slide46

Cosmogenic induced isotopes

Theoretical sea-level Cosmic Ray Flux

(Latitude New York City ≈ LNGS)

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.

7Be is efficiently removed by distillation!

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

slide47

14C

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

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!

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

slide48

Regular N2

High Purity N2

LAK (Low Ar/Kr content) N2

Air contaminants: 222Rn, 85Kr, 39Ar

N2 Plant

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

85Kr

β emitter: Emax = 687 keV

(Eγ = 514 keV)

Half-life: 10.8 years

N2 used to sparge scintillator

39Ar

βemitter: Emax = 565 keV

(no gamma)

Half-life: 269 years

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

slide49

sketch of N2 Plant

  • 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 usuallyis below 1 µBq/m³ (STP). The output can be up to 100 m³/h.

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

slide50

Water plant

Deionization Unit

Reverse Osmisis

Ultra Filters

Nitrogen Stripping

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

slide51

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

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

slide52

Installation of the US Skids

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

slide53

Installation of the US Skids

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

slide54

Geoneutrinos detection in Borexino

Earth emits a tiny heat flux with an

average value of

ΦH~ 60 mW/m2

Integrating over the Earth surface:

HE ~ 30 TW

Detecting antineutrino

emitted by the

decay of radioactive isotopes

It is possible to study the

radiochemical composition of the Earth

Giving constrain on the heat generation within the Earth.

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

slide55

238U 232Th 40K

Radioelements

The 235U chain contribution can be neglected

(ε is the present natural isotopic abundance)

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

slide56

Principle of

anti-neutrino

detection

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

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

slide57

238U and 232Th chains have 4 βwith E > 1.8 MeV :

Anti-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 and

low energy component coming with contributions from U + Th chains

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

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

slide58

KamLAND

Experimental investigation of geologically

produced antineutrinos with KamLAND

Nature vol 436 july 20 2005

Reactors

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

13C(α,n)16O

210Pb

210Bi

210Po

α=5.30 MeV

210Pb

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

slide59

Background from nuclear

Reactors

No working nuclear plants in Italy

The nearest are at about 700 km

Borexino

is located in the

Gran Sasso underground laboratory (LNGS)

in the center of Italy:

42°N 14°E

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

Data from the International Nuclear Safety Center(http://www.insc.anl.gov)

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

210 pb concentration measured in the counting test facility
210Pb concentration measured in the Counting Test Facility

Background from Po-210

  • 210Pb related background negligible
  • Only significant source of background are nuclear reactors
  • Accidental rate also negligible (< 10% of reactors background)

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

slide61

Positron energy spectrum from antineutrino events in Borexino

The number expected events in Borexino are:

The background will be:

U+Th

European Reactors

Predicted accuracy of about 30%

in 5 years of data taking

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

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