MOON...Molybdenum Observatory Of NeutrinosH. Ejiri et al. PRL 85 (2000) 2917

•Low Energy Solar Neutrino Spectroscopy

• Search for 0 in 100Mo

• Supernova Neutrino

Peter Doe, University of WashingtonNeSS 2002, Washington DC, 19 - 21 September, 2002

Physics Goals:

100Mo

Why Low Energy Solar Neutrinos?

• Eth = 0.168 MeVpp + 7Be Solar Neutrino spectroscopy in real-time

• Large CC ratesRaw rates/ton100Mo/year = 40 7Be, 120 pp

• Signal = Two coincidenceSuppress backgrounds

• Directly determine neutrino absorption cross section - Garcia et al.

Solar- capture rates (SNU)Nucleus Q (MeV) pp 7Be 13N pep 15O 8B Total

37Cl a 0.814 0 1.1 0.1 0.2 0 6.1 7.940Ar b >1.505 0 0 0 0 0 7.2 7.271Ga c 0.236 78 35 3.7 2.9 5.8 12.9 132

100Mo d 0.168 639 206 22 13 32 27 965115In a 0.120 468 1 13.6 8.1 18.5 14.4 639

A; Bahcall 88, b; Bhattacharya, c; Ejiri 98, d; Ejiri 99

Why 100Mo?

• Mass 100Mo 1 ton• Purity mBq/ton for U, Th isotopes• Time resolution 2 Coincidence

T~1 30s (solar & Supernova ), 2ns ( )

• Spatial Resolution V~10-9 ~3mm (solar & Supernova )

• Energy resolutionE~0.12/E 1/2 Mev (~7% at 3 MeV)

• Dynamic rangeE ~0.1 40 MeV (solar & Supernova )

Inverse beta decay: E= 0.115 MeV Followed by: Beta decay 100Tc: E= 0.63.2 MeV, =16s

Solar Neutrino Signal:

Detector Requirements:

Scintillator Mo Foil Sandwich• Mo loaded liquid scintillator• Cryogenic calorimeter

One possible configurationscintillator

Mo foilReadout fibers1 module:

Mo foil, 6m x 6m x 0.05 gm/cmScintillator 6m x 6m x 0.25cm 222 wavelength shifting fibers

Super module (detector)1950 Modules6m x 6m x 5m34 t nMo (3 t 100Mo)13600, 16-anode PMT readout

Rate pp - 7Be ~ 0.3 - 0.1 /ton/day

Detection Techniques under Consideration:

• Mo Loaded Liquid Scintillator0.3 -0.7% Mo by weight ~3.5 103 photons/MeV

• Avalanche Photo diode readoutHigh quantum efficiency

• Wavelength shifting fiber readout

E~2E-1/2~11% at 3MeVX~0.8 E-1/2~0.5cmNeed to increase photon yield by 2.5

Anticipate ~2 year R&D, then freeze detector design

Ongoing R&D:

• Depth > 4000 mwe• Radon < 10 Bq/m3 (10 mBq/m3 in detector)• Cavity ~ 10m, 10m, 20m (includes staging area)

+ counting and control room

H.Ejiri, N. Kudomi,s. YoshidaRCNP, Osaka Univ. Japan

R. Hazama, K. Nomahci, K. Matsuoka, Y. SugayaPhys. Dept. Osaka Univ. Japan

P.J. Doe, V. Gehman, R.G.H. Robertson, J.F. Wilkerson, D. WillCENPA, Univ. Washington Seattle, USA

J. EngelPhys. And Astronomy, Univ. North Carolina, USA

P. Krastev, IAS, Princeton, USA

M. FingerPhys. Dept., Charles Univ., Prague, Czech Republic

A. Gorin, I.Manouilov, A. RjazantsevInst. High Energy Physics, Protvino, Russia

In Association with:

The Majorana CollaborationF. Avignone, C. AalsethS.R. Elliott, H. Miley…...

Laboratory Requirements:

The MOON Collaboration: