XV IFAEIncontri sulla Fisica delle Alte Energie

Lecce, 23-26 Aprile 2003

N. FerrariLaboratori Nazionali del Gran Sasso

Esperimenti per la Rivelazionedei Neutrini Solari

pep = 1.44 MeV 4.77 108 1.5 %

… and …

CNO < 1.7 MeV 1.02 109 20 %hep = 18.8 MeV 9.3 103 100 %

pp < 420 keV 5.95 1010 1 %

7Be

8B

= 891 keV (90%)

= 380 keV (10%)

4.77 109 10 %

< 14 MeV 5.05 106 18 %

Energy Φcm-2s-1 δΦ

νtype

Neutrinos from the SunN. Ferrari XV IFAE

The Chlorine experiment

Location: Homestake Gold Mine, South Dakota (USA) 4500 mweTarget: 615 tons of C2Cl4

Neutrino interaction: 37Cl (νe , e) 37ArThreshold : 814 keV

Detection Technique: radiochemical

37Ar is extracted from the tank by He purgingevery two months, and then counted insidea gas proportional counter

Signal composition:

8B 76.5 %7 Be 15.1%

cno 5.5%

pep

2.9%

The C2Cl4 tank

N. Ferrari XV IFAE

Data taking: 1970 – 1995 108 solar runs.

Results:ν interaction rate on 37Cl: 2.56 +- 0.16 (stat) +- 0.16 (sys) SNU

R (exp/SSM) = 0.34 +- 0.03 (exp) +- 0.05 (theo)

R. Davis, Nobel prize 2002

Results from single extractions

THE ASTROPHYSICAL JOURNAL, 496:505-526, 1998 March 20

FIRST EVIDENCE FOR NEUTRINOS COMING FROM THE SUNFIRST EVIDENCE FOR DEFICIT IN THE SOLAR NEUTRINO FLUX

N. Ferrari XV IFAE

The Kamiokande experiment

Location: Kamioka mine, Japan, 2700 mwe depth

Target: 4500 tons of pure water2150 tons (fid. Vol.)

Neutrino interaction: e + νx e + νx (CC+NC)

Detection Technique: Cerenkov light of scattered electron

Signal composition: 100% from 8B νDirection of recoil electronEnergy spectrum of recoil electron

Threshold : 7 MeV

νx

e

Data taking: 1987 1995 2079 days of live-time.

948 PMTs

Outer tank

Inner tank

N. Ferrari XV IFAE

Results : 597 ν events observed in 2079 daysΦ(8B) = 2.80 +/- 0.19 (stat) +/- 0.33 (sys) 106 cm-2 s-1

R (exp/SSM) = 0.37Confirmation of the evidence for a “solar neutrino problem”

M. KoshibaNobel prize 2002

Kamiokande III, direction cos tsun

Kamiokande II, direction cos tsun

First evidence that neutrino signals are correlated with the Sun direction

Kamiokande II+III, energy spectrum

First test of the 8B neutrino energy spectrum

Kamiokande II+III, day-night asimmetry

First measurement of solar neutrinos in real time

N. Ferrari XV IFAE

The Gallium Experiments

GALLEX/GNOLocation:Laboratori Nazionali del Gran Sasso

Abruzzo (Italy)

SAGELocation:Baksan Neutrino Observatory

Caucasus (Russia)

Neutrino interaction: 71Ga (νe , e) 71Ge Threshold : 233 keV

Target: 101 tons of GaCl3 acidic solution(30 tons of nat. Ga)

Target: 55 tons of metallic Ga

Signal composition:

pp 54.5 %

pep 2.2

%

7 Be 26.8

%cn

o 7.0%

8 B 9

.5 %

N. Ferrari XV IFAE

GALLEX/GNO SAGE

Detection Technique: radiochemical71Ge is extracted from the solution by N2 purgingevery 4 weeksIt is then counted inside gas proportional counters

Detection Technique: radiochemical71Ge is extracted from the reactors by a chemicalprocedure every 4-5 weeks.It is then counted inside gas proportional counters

N. Ferrari XV IFAE

GALLEX/GNO SAGE

Data taking: 1991 – ongoing Data taking: 1991 – ongoing

Results: (Runs 1-108) (May 91- Jan 02)70.8 +- 4.5 (stat) +- 3.8 (sys) SNUR (exp/SSM) = 0.55 +- 0.05 (exp) +- 0.03 (theo)

Results: (Runs 1 – 104) (Jan 90 – Jan 03)70.5 +- 4.8 (stat) +- 3.5 (sys) SNUR (exp/SSM) = 0.55 +- 0.05 (exp) +- 0.03 (theo)

FIRST DETECTION OF PP SOLAR NEUTRINOS

SUPPRESSION OF INTERMEDIATE ENERGY SOLAR NEUTRINO FLUX

N. Ferrari XV IFAE

SuperkamiokandeLocation: Kamioka Mozumi Mine (Japan)Target: 50 Ktons of ultrapure water

(22.5 ktons fid. Vol.)

Neutrino interaction: e + νx e + νx(CC+NC)

Detection Technique: Cerenkov light of scattered electron

Signal composition: 100% from 8B νDirection of recoil electronEnergy spectrum of recoil electron

Threshold : 5 MeV

Data taking: 1996 – 2001 1496 days of live-time.

November 2001 : ½ of the PMTs destroyedNovember 2002 : Data taking restarted

N. Ferrari XV IFAE

Results:

22000 ν events observed in 1496 days

Φ(8B) = 2.35 +- 0.025 +- 0.065 106 cm-2 s-1

R (exp/SSM) = 0.465 +/- 0.005 +/- 0.013

Clear “image” of the Sun with neutrinos

Seasonal variation of the flux

Precision test of the 8B ν energy spectrum

N. Ferrari XV IFAE

The Sudbury Neutrino Observatory

Location:Sudbury mine, CanadaTarget: 1000 tons of heavy water

Neutrino interactions:e + νx e + νx ES

strong directional sensitivityνe + d p + p + e CC

sensitive to νe only!weak directional sensitivity 1-1/3cos(t)

νx + d p + n + νx NCsensitive equally to all flavours

Detection Technique:Cerenkov light from electronsGamma from n capture

Data taking:Phase I Nov 1999 – May 2001 (pure D2O)Phase II Jun 2001 – ongoing (“salt phase”)Phase III “3He detectors”

9500 PMTs

H2O shielding

Acrylic vessel

D2O

N. Ferrari XV IFAE

Φe (8B) = (1.76 +/- 0.10) 106 cm-2 s-1

Φµ,τ (8B) = (3.41 +/- 0.64) 106 cm-2 s-1

Φ (8B) = (5.09 +/- 0.62) 106 cm-2 s-1

Results: Phase I306.4 days of live time

Energy threshold : 5 MeVν events: 1968 CC, 577 NC, 263 ES

STRONG EVIDENCE FOR FLAVOUR CHANGE !8B ν flux (sum over all flavours) in agreement with SSM

N. Ferrari XV IFAE

2002 : SNO results

Bahcall, Gonzalez-Garcia hep-ph/0204314

2003 : KAMLAND

Bahcall, Gonzalez-Garcia hep-ph/0212147

10-5 10-4 10-3 10-2 10-1 1 10

10-11

10-10

10-910-8

10-7

10-6

10-510-410-3

10-2

10-1

Solar Neutrino Oscillations

2001 : Final SK-I res.

Bludman, Langacker Phys. Rev. D47, 1993

1998: first SK results

Bahcall, Krastev, Smirnov Phys. Rev. D58, 1998

N. Ferrari XV IFAE

∆m2

tg2(t)

Solar Solar neutrino neutrino experimentsexperiments::what nextwhat next??

N. Ferrari XV IFAE

8B neutrinos :

7Be neutrinos :

pp neutrinos :

CNO neutrinos :

Real time detection of 7Be ν via ES (Borexino / Kamland) detectors ready

Real time detection of 7Be ν via CC (LENS, MOON) R&D

Detection via NC event by event SNO Phase II and Phase III Running

Long-term monitoring of pp ν flux by radiochemical experiments (GNO and SAGE)- Running

Real time detection via ES (Xmass, Genius, CLEAN, Heron) R&D - Prototypes

Radiochemical detection (Lithium project) R&D

Real time detection via ES (Xmass, Genius, CLEAN, Heron) R&D - Prototypes

Real time detection via CC (LENS, MOON) R&D

Neutrino interaction:e + νx e + νx (CC+NC)

Max recoil energy: 665 keV for 7Be ν261 keV for pp ν

Detection Techniques:• Scintillation light produced by the scattered electron

• Ionisation produced by the scattered electron

N. Ferrari XV IFAE

Real time detection of sub-MeV ν via ES

0 .2 0 .4 0 .6 0 .8 1 1 .2 1 .4 1 .60

1

2

3

4

C o s m o g.

B a ckg

S S M

To ta l

S igna l + Background in BOREX INO

re co il e le c tro n k in e tic e n e rg yHMe VL

stnuocyad

VeM

not

N. Ferrari XV IFAE

Status: Detector installedScintillator filling in next future

Status: Running for reactor neutrino detection at long baseline

Upgrading underway

Kamland

Location: Kamioka Observatory (Japan)Target: 1000 t of ultrapure scintillator

300 t fiducial volume

Location: Laboratori Naz. del Gran SassoTarget: 300 t of ultrapure scintillator (PC)

100 t fiducial volume

Borexino

N. Ferrari XV IFAE

Multi-purpose detectors : Dark matter, ββ decay, solar neutrinos

Genius Target: 1 to 10 tons of natural or enriched Germanium detectors

Signal: 1.8 ev/day from pp 0.6 ev/day from 7Be (1 ton det.)

Detection: Ionisation from scattered electronsGermanium NitrogenUnderground Setup

Xmass Target: 10 tons of liquid Xenon

Signal: 10 ev/day from pp 5 ev/day from 7Be (10 ton det.)

Detection: Scint. light from scattered electronXenon MASsive detector

for Solar neutrino

CLEAN Target: 10 tons of liquid Neon

Signal: 10 ev/day from pp 5 ev/day from 7Be (10 ton det.)

Detection: Scint. light from scattered electronCryogenic Low Energy

Astrophysics with Noble gases

Real time detection of sub-MeV ν via CCN. Ferrari XV IFAE

LENS Detection: 115In (νe, e) 115Sn*115Sn

Threshold : 118 keV

Target: Indium loaded liquid scint.

Prompt electrondelayed γ from 115Sn*

τ = 4.8 µs

Low Energy Neutrino Spectroscopy

Status: R&D

MOONMolybdenum Observatory

Of Neutrinos Detection: 100Mo (νe, e) 100Tc100Ru

Threshold : 168 keV

Prompt electrondelayed β from 100Tc

τ = 23 s

Target: Molibdenum foils with plastic fiber scintillatorsor Md loaded liquid scintillator

Status: R&D

Detecting CNO ν

Lithium projectTarget: Metallic Lithium target (10 tons)

Detection: 7Li (νe, e) 7BeRadiochemical technique

7Be decays via EC: 0.55 keV Auger electronsto be detected with cryogenic techniques

Signal composition:

pep 23

,3 %

7 Be 23.3

%

cno 36

.2%

8 B 1

7.5

%Extract CNO signal !!

Status: R&D