The NPD  Experiment David Bowman IScientific goals IIStatus

NPD  Collaboration Institutions –Dayton, Dubna, Hamilton, Indiana, Jlab, KEK, LANL, NIST, ORNL, TRIUMF, Berkeley, Manitoba, Michigan, New Hampshire, Tennessee Sponsors –DoE, NSF, NSERC, LANL, collaborating institutions

Scientific goal of the experiment

Hadronic weak interaction Weak NN force interferes with the strong NN force. Changes parity of the NN pair. Changes I NN by 0, 1, or 2. Produces parity-violating admixtures in nuclear wave functions and PV asymmetries HWI is described by a meson exchange potential

The value of is controversial 18 F gamma circular polarization experiments give 0. Haxton interprets result to give =0± Cs anapole moment gives non-zero value. Flambaum interprets result to give =7± The goal of the NPD  experiment is to measure with an accuracy of Goal error is 5% of the DDH reasonable range.

Status of NPD  experiment 04-5 commissioning run complete 06 production at LANSCE –Measure A  to ±10 -7 Move to SNS in 06-7 –Measure A  to ±10 -8

Apparatus to measure A 

Neutron Intensity Monitors

3 He neutron polarizer

Determine 3 He polarization Stable operation for several weeks 3 He polarization = 46±2%

Commissioning the RFSR FP12 neutron guide RF Spin Rotator 3 He Spin Filter M1 M2

Spin-flipper efficiency Preliminary

Liquid Para-Hydrogen Target 20 liter liquid volume, 30 cm diameter and 30 cm long Absorbs 65% of neutron beam 1% neutron depolarized at 17K (0.05% of LH 2 in ortho-state) due to large scattering cross section No false asymmetries from target material Use 6 Li to shield CsI from neutrons Ortho (total) Para (total) Capture cross section

CsI detector 48 (15cm) 3 modules

noise/counting statistics Electronic noise << counting statistics Experiment operates close to counting statistics limit

Electronic asymmetries (beam off) Time to determine electronic asymmetries << run time False asymmetries are  Asymmetry (10 -8 ) Time (hours) Additive-0.1±.35 Multiplicative-0.8 ±.511

Measured asymmetries Time to determine background asymmetries << run time False asymmetries ~ asymmetry  f-bkg are  Material Time (shifts) f-bkg (%) U-D (PV) Asy.(10 -6 ) L-R (PC) Asy.(10 -6 ) Al ± ±0.3 Cu ± ±2.5 B ± ±3.3 In ± ±2.5 Cl ± ±2.0

Spin interactions

Estimated sizes of false asymmetries

Apparatus performance All components of the apparatus performed as designed Several physics measurements have been

LH target must be finished, tested, and installed We request a thorough-going safety review to insure a safe target.

Beam time request The estimate is based on measured performance – 3 He polarization =.55 –Cell diameter = 10 cm Projected FPNB projected intensity 7000 MWh for data and systematics 1000 h at >,14 MW for tuning and systematics

Schedule We request that NPD  run after the beam line is commissioned –9/06Move to SNS –9/07Beam line ready –12/07Experiment installed –3/08Commissioning complete –6/08Start production

Geoff’s questions Technical issues - hydrogen target Funding $K 2500 already spent for apparatus at LANL –20transport to SNS –160shielding –20supports and stands –20Air conditioning –130target infrastructure –30instrumentation/cabling Safety - hydrogen target Complex installation - one block ~ 40 users 3 PhD’s to date, trained several undergraduate students, Expect several PhD’s from SNS run