Borexino - Institute for Nuclear Theory fileVirginia Tech Sept 2002 NeSS Borexino Status Report R. Bruce Vogelaar for the Borexino Collaboration

Virginia Tech Sept 2002 NeSS

BorexinoStatus Report

R. Bruce Vogelaarfor the Borexino Collaboration


BelgiumI.R.M.M. European Joint Research Center - Geel

CanadaQueen's University - Kingston

FranceCollege de France

GermanyMax-Planck-Institut fuer Kernphysik Heidelberg Technische Universitaet Muenchen

HungaryKFKI-RMKI Research Institute for Particle & Nuclear Physics Budapest

ItalyDipartimento di Fisica Universita' e I.N.F.N di GenovaL.N.G.S. Dipartimento di Fisica Universita' e I.N.F.N. di MilanoDipartimento di Fisica Universita' e I.N.F.N. di PaviaDipartimento di Chimica dell'Universita' e I.N.F.N di Perugia

PolandInstitute of Physics, Jagellonian University. Cracow.

RussiaJ.I.N.R. DUBNA Kurchatov Institute - Moscow

United StatesBell Laboratories, Lucent Technologies Massachusetts Institute of Technology Princeton University Virginia Polytechnic Institute and State University

Collaborating

Institutions


Physics Goals and Detector Concept:

Neutrino Energy

First direct measurement of 7Be solar neutrino flux


and …and …

Solar Physics Geo Neutrinos

SupernovaLong-Baseline Reactor


Gran Sasso 2900m (Italy, Abbruzzo)

LNGS, Hall C

BOREXINO


Above Ground Infra-Structure


Neutrino Detection in BOREXINO

νe,µ,τ e-

e-

Z0

νe,µ,τ

+ NC interaction

νe

νee-

W+

e-

CC interaction

CC (νe)

NC (νµ,τ)

σ

SSM: 55 day -1


BOREXINO - detector


Radiopurity Requirements

14C / 12C < 10-18

U 2 ⋅ 10-17 g/gTh 6 ⋅ 10-16 g/gK 8 ⋅ 10-15 g/g

for 1 background event/day/100twithin the neutrino window (250 - 800 keV)

after all cuts have been applied

Alpha/Beta separation in CTF


BOREXINO: electron recoil spectra


7Be ν 0.86 MeV

SNO,SuperK

coun

ts/d

ay

days

winter wintersummer

no oscillation

∆m = 9•10 eV2 - 1 1 2

∆m = 1.1•10 eV2 - 1 0 2

sin 2 = 0.82

θ

sin 2 = 0.932

θ∆m = 4.2•10 eV

2 - 1 0 2

SK best fit

sin 2 = 0.82

θ

count rate in BOREXINO

day-night variation & seasonal variation

• Different oscillations distinguished at E<1 MeV



Borexino: Installation in Hall C

BorexinoDetector

ElectronicsDAQ

CTF

ScintillatorStorage


Pictorial Status:


Borexino silica gel column purification

Purification:DistillationWater ExtractionSilica Gel ColumnN2 Stripping

N2 purificationOne of two purification plants produced in the US and now operational in Gran Sasso




Vessels received at Gran Sasso and

awaiting installation

Production at Princeton

Test Installation in Gran Sasso


Calibration Source DeploymentSeven cameras used to

locate source to an absolute position of

about +/- 2 cm.Produced at Virginia Tech


1 cm/pixel


Counting Test Facility (III)

Added:

Rn barrier

Muon Veto

Integration with Borexinofluid systems

238U: 238U(α)234Th(β)234Pa(β)234U(α)230Th(α)226Ra(α)222Rn(α)218Po(α)214Pb(β)214Bi(β)

214Po(α)210Pb(β)210Bi(β)210Po(α)206Pb

232Th: 232Th(α)228Ra(β)228Ac(β)228Th(α)224Ra(α)220Rn(α)216Po(α)212Pb(β)212Bi(β)212Po(α)208Pb


Current Program:• vessel installation ! final installations of subsystems

• define scintillator purification strategy using CTF (III)

• check scintillator batches for radiopurity ie: 238U, 232Th, 210Po, 85Kr

• test purification methods: silica gel columnwater extractiondistillationstripping

! Goal: fill with the best scintillator possible, and tryto not rely on post-fill purification

the detector is nearing hardware completion and programmatic issues related to the operational phase are coming to the front


Schedule:

20032002

10

Ready to Take Data

ScintillatorFilling

PC Purification

ScintillatorTesting with CTF

12111098765432112119

currently there is some uncertainty related to results of the current CTF program and safety issues


BorexinoDirect Measurement of the 7Be Solar Neutrino Flux in

the Next Few Years

Documents

Borexino - Institute for Nuclear Theory fileVirginia Tech Sept 2002 NeSS Borexino Status Report R. Bruce Vogelaar for the Borexino Collaboration