Lino Miramonti - 7 February Honolulu Hawaii (USA) 1 Astroparticle Physics at Gran Sasso Underground Laboratory: Borexino and geo-neutrino Lino Miramonti – 7 Feb Honolulu (Hawaii)

Lino Miramonti - 7 February Honolulu Hawaii (USA) 2 Particle physics Astrophysics & Cosmology Astroparticle physics 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 Underground 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.

Lino Miramonti - 7 February Honolulu Hawaii (USA) 4 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 Universit ä t München, Max Planck Institut für Physik Muenchen, Eberhardt, Karls Universit ä t 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 Jyv ä skyl ä 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.

Lino Miramonti - 7 February Honolulu Hawaii (USA) 5 activities 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) JRA1Low background techniques for Deep Underground Science (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 Honolulu Hawaii (USA) 6 JRA1 () JRA1 (Joint Research Activities 1) (LBT-DUSL) Low background techniques for deep underground sciences (LBT-DUSL) Objectives:  Background identification and measurement (intrinsic, induced, environmental)  Background rejection techniques (shielding, vetoes, discrimination) Objectives:  Background identification and measurement (intrinsic, induced, environmental)  Background rejection techniques (shielding, vetoes, discrimination) 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

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Lino Miramonti - 7 February Honolulu Hawaii (USA) 8 LNGS permanent staff: 60 (physicists, technicians, administration) Scientists involved in LNGS experiments: 700 from 24 countries

Lino Miramonti - 7 February Honolulu Hawaii (USA) 9 Operating Institution Istituto Nazionale di Fisica Nucleare (INFN) LocationGran Sasso Tunnel (Abruzzi, Italy) Excavation1987 Underground area3 halls A B C (100m x 18m x 20m) + service tunnels Depth1400 m (3800 mwe) Total volume m 3 Surface> 6000 m 2 3 main halls A B C 100 x 18 m 2 (h.20 m)

Lino Miramonti - 7 February Honolulu Hawaii (USA) 10 Muon Flux 1.1 μ m -2 h -1 Primordial Radionuclides 238 U6.8 ppmRock(Hall A) 0.42 ppmRock(Hall B) 0.66 ppmRock(Hall C) 1.05 ppmConcreteAll Halls 232 Th2.167 ppmRock(Hall A) ppmRock(Hall B) ppmRock(Hall C) ppmConcreteAll Halls K160 ppmRock Neutron Flux n cm -2 s -1 ( eV) n cm -2 s -1 (0.05 eV- 1 keV) n cm -2 s -1 (1 keV-2.5 MeV) n cm -2 s -1 (> 2.5 MeV) Backgrounds & LNGS Residual muon flux (6 order of magnitude lower than surface) Coming from spontaneus fission (in particular from 238 U) 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 238 U than Hall B and Hall C (and 30 times more radioactive in 232 Th)

Lino Miramonti - 7 February Honolulu Hawaii (USA) 11 HPGe Hall (32 m 2 floor) FACILITY FOR LOW-LEVEL RADIOACTIVITY MEASUREMENTS Present: 32 m 2 on one floor in service tunnel Future: 60 m 2 distributed on three floors in hall A Courtesy by Matthias.Laubenstein

Lino Miramonti - 7 February Honolulu Hawaii (USA) 12 Completed experiments Atm ν, MonopolesMACRO (Streamer tubes + Liquid scintillators) Solar neutrinosGALLEX / GNO (~ 30 T Gallium radiochemical detector) ββHeidelberg-Moscow (~ 11 kg enriched 76Ge detectors) Mibeta (~ 7 kg Bolometers TeO 2 ) Dark MatterDAMA (~ 100 kg NaI detectors)

Lino Miramonti - 7 February Honolulu Hawaii (USA) 13 Running experiments ββCuoricino(~ 41 kg TeO 2 crystals) Dark MatterCRESST(Sapphire cryodetector & CaWO 4 crystals (phonons+scintillation)) LIBRA(~ 250 kg NaI crystals) HDMS / Genius-TF(Ge detector 73 Ge enriched) Supernova neutrinosLVD(Streamer tubes + Liquid scintillator) Nuclear astrophysicsLUNA(Accelerator)

Lino Miramonti - 7 February Honolulu Hawaii (USA) 14 Under construction CERN-GS beam ν OPERA(Emulsion) ICARUS(~ 600 T Liquid Argon) Solar NeutrinosBorexino(~ 300 T Liquid scintillator) Planned & proposed ββ CUORE(~ 750 kg Te0 2 ) GERDA( 76 Ge) Nuclear astrophysicsLUNA-III Gravitational wavesLISA R&D Dark matterLiquid Xe / Liquid Ar

Lino Miramonti - 7 February Honolulu Hawaii (USA) 15 RADIOCHEMICAL Integrated in energy and time CHERENKOV Less 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.

Lino Miramonti - 7 February Honolulu Hawaii (USA) 16 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 Honolulu Hawaii (USA) 17 BOREXINO: subsystems Scintillator purification systems:  Water extraction  Vacuum distillation  Silicagel adsorption DI Water plant Storage tanks: 300tons of PC Borexino detector Control room Counting room CTF

Lino Miramonti - 7 February Honolulu Hawaii (USA) 18 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) 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 Honolulu Hawaii (USA) 19 E ν = 862 keV (monochromatic) Φ SSM = 4.8 · 10 9 ν s -1 cm 2 Recoil nuclear energy of the e - expected rate (LMA hypothesis) is 35 counts/day in the keV energy range Elastic Scattering

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Lino Miramonti - 7 February Honolulu Hawaii (USA) 34 Cleen Room (on top of the Water Tank) for the insertions of lasers and sources for calibrations.

Lino Miramonti - 7 February Honolulu Hawaii (USA) 35 Cleen Room (on top of the Water Tank) for the insertions of lasers and sources for calibrations.

Lino Miramonti - 7 February Honolulu Hawaii (USA) 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

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Lino Miramonti - 7 February Honolulu Hawaii (USA) 38 The CTF as a tool for tuning the apparatus before filling In this moment we use the CTF in order In this moment we use the CTF in order:  To asses the performances of the different BOREXINO sub- systems.  To test the 14 C 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 Honolulu Hawaii (USA) 39 1.Natural radioactivity 2.Muon Induced reactions 3.Cosmogenic induced isotopes C 5.Air contaminants: 222 Rn, 85 Kr, 39 Ar 1.Natural radioactivity 2.Muon Induced reactions 3.Cosmogenic induced isotopes C 5.Air contaminants: 222 Rn, 85 Kr, 39 Ar

Lino Miramonti - 7 February Honolulu Hawaii (USA) 40 Primordial radioactivity: ( about 20 radioisotopes with half-life > Earth life) between them: 238 U and 232 Th (α and β emitters) 40 K (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

Lino Miramonti - 7 February Honolulu Hawaii (USA) 41 Typical Conc.Borexino level 238 U, 232 Th~ 1ppm in dust ~ 1ppb stainless steel ~ 1ppt IV nylon ~ g/g (PC) ~ g/g (water) K nat ~ 1ppm in dust< g/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.

Lino Miramonti - 7 February Honolulu Hawaii (USA) 42 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 ( keV) the alpha I dentification efficiency range from 90 to 97 % with an associated beta misidentification of ~ 10%.

Lino Miramonti - 7 February Honolulu Hawaii (USA) Rn 218 Po 214 Pb 214 Bi 214 Po 210 Pb T=163 µs α=5.49 MeV α=6.02 MeV α=7.69 MeV 210 Bi 210 Po 210 Pb α=5.30 MeV

Lino Miramonti - 7 February Honolulu Hawaii (USA) Rn 216 Po 212 Pb 212 Bi 212 Po 208 Pb T=19.8 m T=0.3 µs 208 Tl 224 Ra α=5.68 MeV α=6.29 MeV α=6.792 MeV α=8.79 MeV α=6.04 MeV

Lino Miramonti - 7 February Honolulu Hawaii (USA) 45 Muon Induced reactions At LNGS we have 1.1 µ m 2 h -1 with a = 320 GeV 11 Beτ = 13.8 sβ-β- 7 Beτ = 53.3 dβ - EC 11 Cτ = 20.4 mβ - EC 10 Cτ = 19.3 sβ - EC These elements having a τ > 1 s is not possible to tag them Interacting with 12 C 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 Ultrarelativistic µ can produce n which after been captured by p give a 2.2 MeV γ ray:

Lino Miramonti - 7 February Honolulu Hawaii (USA) 46 Cosmogenic induced isotopes 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 12 C producing 7 Be: 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) 7 Be is efficiently removed by distillation!

Lino Miramonti - 7 February Honolulu Hawaii (USA) C Typical Conc.Borexino level 14 C/ 12 C < C/ 12 C ~ The 14 C 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 14 C! The reactions expected to contribute the most to 14C production in deep underground geological formations are:

Lino Miramonti - 7 February Honolulu Hawaii (USA) 48 Air contaminants: 222 Rn, 85 Kr, 39 Ar Regular N 2 High Purity N 2 LAK (Low Ar/Kr content) N 2 N 2 used to sparge scintillator OriginTypical Conc. (in air) Borexino level 222 Rn 238 U chain Bq/m 3 ~ 70  Bq/m 3 in PC 85 Kr Anthropogenic origin (nuclear fue reprocessing) 1 Bq/m³ 0.16  Bq/m 3 in N 2 39 Ar Cosmogenic production11 mBq/m³ 0.5  Bq/m 3 in N 2 85 Kr β emitter: E max = 687 keV (Eγ = 514 keV) Half-life: 10.8 years 39 Ar β emitter: E max = 565 keV (no gamma) Half-life: 269 years To reduce the effect of emanation we used only electroplisched stainless steel, applied orbital weldings.

Lino Miramonti - 7 February Honolulu Hawaii (USA) 49 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 N 2 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 222 Rn is usually in the range of 0.1 – 0.2 mBq/m³ (STP). For the High Purity N 2 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 226 Ra (less than 0,3 mBq/kg)). For the evaporation we use an electrical evaporator with only low surface. The level of 222 Rn is usually is below 1 µBq/m³ (STP). The output can be up to 100 m³/h.

Lino Miramonti - 7 February Honolulu Hawaii (USA) 50 Deionization Unit Reverse Osmisis Nitrogen Stripping Ultra Filters

Lino Miramonti - 7 February Honolulu Hawaii (USA) 51 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 Honolulu Hawaii (USA) 52 Installation of the US Skids

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

Lino Miramonti - 7 February Honolulu Hawaii (USA) 54 Earth emits a tiny heat flux with an average value of Φ H ~ 60 mW/m 2 Integrating over the Earth surface: H E ~ 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

Lino Miramonti - 7 February Honolulu Hawaii (USA) 55 (ε is the present natural isotopic abundance) 238 U 232 Th 40 K The 235 U chain contribution can be neglected

Lino Miramonti - 7 February Honolulu Hawaii (USA) 56 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 Honolulu Hawaii (USA) U and 232 Th chains have 4 β with E > 1.8 MeV : end.point [Th-chain] 228 Ac< 2.08 MeV [Th-chain] 212 Bi< 2.25 MeV [U-chain] 234 Pa< 2.29 MeV [U-chain] 214 Bi< 3.27 MeV Anti-neutrino from 40 K 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 Honolulu Hawaii (USA) C(α,n) 16 O Reactors Nature vol 436 july Experimental investigation of geologically produced antineutrinos with KamLAND α’s are produced by 210 Po that created by the 210 Pb (τ = 22.3 y) 210 Pb 210 Bi 210 Po 210 Pb α=5.30 MeV KamLAND

Lino Miramonti - 7 February Honolulu Hawaii (USA) 59 Borexino is located in the Gran Sasso underground laboratory (LNGS) in the center of Italy: 42°N 14°E Calculated anti-ν e flux at the Gran Sasso Laboratory (10 6 cm -2 s -1 ) UThTotal (U+Th)Reactor BKG CrustMantleCrustMantle Data from the International Nuclear Safety Center ( Background from nuclear Reactors Earth data from F. Mantovani et al., Phys. Rev. D 69 (2004) No working nuclear plants in Italy The nearest are at about 700 km

Lino Miramonti - 7 February Honolulu Hawaii (USA) Pb concentration measured in the Counting Test Facility Background from Po Pb related background negligible Only significant source of background are nuclear reactors Accidental rate also negligible (< 10% of reactors background)

Lino Miramonti - 7 February Honolulu Hawaii (USA) 61 The number expected events in Borexino are: The background will be: Predicted accuracy of about 30% in 5 years of data taking