Neutron Spin Rotation Measurements Murad Sarsour for the NSR Collaboration Georgia State University PPNS 2018 International Workshop on Particle Physics at Neutron Sources 2018 May 24-26, 2018 ILL, Grenoble, France 5/25/2018 M. Sarsour, GSU 1
NSR n+ 4 He in DDH n- 4 He is a simple enough system that P-odd spin rotation can be related to weak NN amplitudes. GFMC calculations possible ( Carlson, Wiringa, Nollett, Schiavilla, Pieper ) Existing calculation: Dmitriev et al. Phys Lett 125 , 1 (1983) 0 − 0.22ℎ 𝜕 1 + 0.32ℎ 𝜍 0 − 0.11ℎ 𝜍 1 rad/m 𝜚 𝑄𝑊 𝑜, 4 He = − 0.97𝑔 𝜌 + 0.22ℎ 𝜕 The linear combination of NN weak amplitudes in n+ 4 He spin rotation is ~orthogonal to existing constraints from past measurements using protons (p, 4 He) and anapole moment measurements in odd-proton systems addition of n+ 4 He gives strong constraints. n+ 4 He and n+ 3 He both measure approximately the same linear combination of weak amplitudes, providing a strong check. However, there is no dependence on the isotensor component in n+ 4 He, an important distinction between the two experiments. 5/25/2018 M. Sarsour, GSU 2
NSR n+ 4 He in EFT+ large- N c Impact of new/potential experiments on the current status! • S. Gardner, W.C. Haxton, B.R. Holstein, arXiv:1704.02617v1 (2017) ±𝟐 ± 𝟐 × 𝟐𝟏 −𝟖 Implies the following regarding NSR (n+ 4 He): Dependence only on LO LEC ( Λ 0 + ) with relatively large expectation value No dependence on the isotenor component as in n+ 3 He case Very important distinction between the two experiments Planned NSR at NGC/NIST is expected at [ 1(stat) 1(sys)] × 10 -7 which is several sigmas away from zero according to prediction First quantitative test of SM involving quark-quark Weak interactions in nucleons 5/25/2018 M. Sarsour, GSU 3
NSR-2 Apparatus on NG-6 Beamline at NIST 5/25/2018 M. Sarsour, GSU 4
NSR-2: Measurement Principle PNC of Transversely Polarized Neutrons • y x B z PC PC PNC _ Detector k + PNC Polarizer, P Analyzer, A k N 𝑒𝜚 𝑄𝑂𝐷 ~10 −7 rad/m 1 N N Expected size sin 𝑒𝑨 PNC PA N N Experimental challenges Reducing Ԧ • 𝜏 ∙ 𝐶 → 𝜚 𝑄𝐷 Effectively canceling what is left • Controlling noise • Controlling other systematics • 5/25/2018 M. Sarsour, GSU 5
NSR-2: Apparatus • Snow et al., Rev. Sci. Instrum. 86 , 055101 (2015) Micherdzinska et al. , Nucl. Instrum. Methods Phys. Res., Sect. A 631 , 80 (2011) • Bass et al. , Nucl. Instrum. Methods Phys. Res., Sect. A 612 , 69 (2009) • 6 5/25/2018 M. Sarsour, GSU
NSR-2: Apparatus 5/25/2018 M. Sarsour, GSU 7
NSR-2: Results Snow et al., PRC 83 , 022501(R) (2011) & RSI 86 , 055101 (2015) 𝑒𝜚 𝑄𝑂𝐷 NIST-NG6 = [1.7 ± 9.1 𝑡𝑢𝑏𝑢 ± 1.4 𝑡𝑧𝑡 ] × 10 −7 𝑠𝑏𝑒/𝑛 2008 𝑒𝑨 8 5/25/2018 M. Sarsour, GSU
Toward an improved NSR-3 measurement Snow et al., PRC 83 , 022501(R) (2011) & RSI 86 , 055101 (2015) ? 𝑒𝜚 𝑄𝑂𝐷 𝑒𝜚 𝑄𝑂𝐷 NIST-NG6 ֜ = [1.7 ± 9.1 𝑡𝑢𝑏𝑢 ± 1.4 𝑡𝑧𝑡 ] × 10 −7 𝑠𝑏𝑒/𝑛 ≤ 2 × 10 −7 𝑠𝑏𝑒/𝑛 2008 𝑒𝑨 𝑒𝑨 NG-C: High-flux cold beam for fundamental neutron physics experiments at NIST. Ballistic guide; 11 cm x 11 cm at output • • Curved guide (no line-of-sight to reactor) NG-C Thermal capture fluence rate ≈ 8x10 9 /cm 2 /s • NG-6 9 10/26/2017 DNP MEETING FALL2017
NSR-3: Cryogenics & Target Improvements 120 NSR- II “Reactor On” days Cryomech pulse-tube liquefier: Apparatus inoperable • Tested for 3 months of Analyzed data continuous operation Refilling LHe, Maintenance Observed liquefaction rate • Administration Changing from warm gas of 12 L/day target state Automated operation capable Calibration & • Discarded – targets Systematics of handling ~550 mW heat improperly filled measurement load He re-liquefier removes necessity of LHe fills (~20% of lost NSR-2 time) • Improved cryogenic design for reduced heat load, simpler assembly/disassembly, and more robust operation R&D on new LHe pump to reduce target change • time 5/25/2018 M. Sarsour, GSU 10
NSR-3: Other Beam-Line Components Built at UNAM Procured by NIST Input / Output Coils SM Polarizer/Analyzer Procured by BARC in India SM Guides 10cm × 10cm, 1.25m and 2.0m non-magnetic supermirror neutron guides (NiMo-Ti) m = 2.0, R >90%, matching NGC phase space SM benders (m=2.5) have a • depolarization probability transmission of greater than 90% for / bounce <1% one spin state and a transmission of less than 0.5% for the other spin state 5/25/2018 M. Sarsour, GSU 11
Toward an improved NSR-3 measurement 120 NSR- II “Reactor On” days Snow et al., PRC 83 , 022501(R) (2011) & RSI 86 , 055101 (2015) Apparatus inoperable 𝑒𝜚 𝑄𝑂𝐷 NIST-NG6 Analyzed = [1.7 ± 9.1 𝑡𝑢𝑏𝑢 ± 1.4 𝑡𝑧𝑡 ] × 10 −7 𝑠𝑏𝑒/𝑛 2008 data 𝑒𝑨 Refilling LHe, Maintenance Administration Changing 𝑒𝜚 𝑄𝑂𝐷 Goal: ≤ 2 × 10 −7 𝑠𝑏𝑒/𝑛 target 𝑒𝑨 state Calibration & Discarded – Systematics targets measurement improperly filled 4.5 10 8 /cm 2 /s NG6 8 10 9 /cm 2 /s NGC Counting Stats 5cm × 5cm NG6 10cm × 10cm NGC Stat float glass guides (m=0.68) super-mirror guides (m=2) Reduce heat load Low duty factor Reduce fill/drain times New Polarizer/Analyzer Improve PA Syst 100 G 10 G in target region Reduce B field in target region Be filter cuts spectrum <4Å to limit under rotation by pi-coil ± 9.1 ( stat ) ± 1.4 ( sys ) ± 1.0 ( stat ) ± 1.0 ( sys ) 12 10/26/2017 DNP MEETING FALL2017
NSR-3 Status Supermirror Waveguides (new / BARC) Commissioned at LANSCE FP12 o Tested (October 2014 at LENS) & used for the exotic spin- Input/output coils (new / UNAM) dependent interaction search exp’t New supermirror polarizer and analyzer (new / $$$ NIST) o Tested at LENS Pi-coil (new / IU) Ion chamber (new / IU) o Tested and functioning as expected Data Acquisition – Ready o Liquid helium target Cryostat Helium re-liquefier commissions with equivalent heat load o Target and He pump construction and testing in progress 5/25/2018 M. Sarsour, GSU 13
Why NSR-F5 Apparatus at LANSCE FP12? Generic interaction between fermions with a light spin-1 particle arising in a number of Beyond the Standard Model Theories from, e.g., spontaneous breaking of new symmetries. Piegsa& Pignol, PRL 108 , 181801 (2012) 𝜔 𝑊 𝛿 𝜈 + 𝐵 𝛿 𝜈 𝛿 5 𝜔𝑌 𝜈 ℒ = ത Haddock et al., NIM A 885 , 105 (2018) Axial-vector term Induces spin dependent interaction Need polarized particles to probe! Look at the induced spin-velocity interaction between a particle considered as a source and another polarized probe particle. Probe spin-dependent interactions in the mm - µm regime. 2 𝑓 −𝑛 0 𝑠 1 + 1 𝑊 𝐵𝐵 ∝ 𝐵 𝜏 ∙ Ԧ 𝑤 × Ԧ Ԧ 𝑠 𝑠 𝜇 𝑑 𝑠 5/25/2018 M. Sarsour, GSU 14
NSR-F5 Results 𝜚 ′ = [2.8 ± 4.6 𝑡𝑢𝑏𝑢 ± 4.0 𝑡𝑧𝑡 ] × 10 −5 𝑠𝑏𝑒/𝑛 Submitted to PLB 5/25/2018 M. Sarsour, GSU 15
Summary & Outlook Significant recent theoretical work Prediction of a relatively large size for the neutron spin rotation of , ~ 7 10 -7 rad/m without sensitivity to the isotensor component of the NN weak interaction - a strong distinction between n+ 3 He and n+ 4 He. n+ 4 He provides the first test of the SM in the NN weak sector. A substantially improved apparatus was used to make significant improvement in limits on spin-dependent fifth forces using a room temperature target. The NSR-3 collaboration has an apparatus nearing readiness for an n- 4 He spin rotation measurement at the level < ± 1.0 (stat) ± 1.0 (sys) rad/m. The critical path items are the LHe pump, LHe target, and radiation shielding. The goal is to be ready for beam in 2019. 5/25/2018 M. Sarsour, GSU 16
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