Status of FNPB Geoff Greene Nadia Fomin University

Status of FNPB Geoff Greene / Nadia Fomin University of Tennessee 1

Spallation Neutron Source at ORNL • 1. 4 Ge. V protons, 60 Hz • H 2 moderator • LHg Spallation target -> neutrons • 17 m SM guide, curved 2

Target, Reflectors, and Moderators Cryogenic H 2 moderators Proton Beam Be reflector Mercury target Ambient H 2 0 moderator Steel reflector 3

Flight Path 13 4

SNS Will Eventually Have 24 Neutron Flight Paths 11 A - Powder Diffractometer Commission 2007 9 – VISION 7 - Engineering Diffractometer IDT CFI Funded Commission 2008 6 - SANS Commission 2007 12 - Single Crystal Diffractometer Commission 2009 5 - Cold Neutron Chopper Spectrometer Commission 2007 13 - Fundamental Physics Beamline Commission 2008 4 B - Liquids Reflectometer Commission 2006 14 B - Hybrid Spectrometer Commission 2011 4 A - Magnetism Reflectometer Commission 2006 15 – Spin Echo 17 - High Resolution Chopper Spectrometer Commission 2008 18 - Wide Angle Chopper Spectrometer Commission 2007 3 - High Pressure Diffractometer Commission 2008 1 B - Disordered Mat’ls Commission 2010 2 - Backscattering Spectrometer Commission 2006 5

Flight Path 13 • 13 A – UCN Beamline • n. EDM • 13 B – Cold Neutrons • NPDGamma 6

FNPB Performance Matches Model Predictions 7

SNS is now fully operational ~9 months of scheduled beam delivery per year 8

Reliability against schedule is quite good Beam Delivery ~450 MWhrs/month Accelerator Power typically ≥ 1 MW and slowly increasing 9

Required Data Collection David estimates that we need ~ 80 FULL MW-days of LH 2 data* to attain a statistical sensitivity of ~10 -8 on Aγ. This estimate includes current best estimates of flux, polarization, transmission efficiencies, choppers bandwidth, run cycle losses, etc. This estimate does NOT include LH 2 reliability At 450 MW-hrs/month, this implies that we need ~4. 2 calendar months of live LH 2 data. *An additional ~12 days of Al data is estimated to be required 10