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Стандартная Модель и структура нуклонов G v = 0.9755 ± 0.0005 G a = 1.245 ± 0.003

PRECISION MEASUREMENT OF THE RATE OF MUON CAPTURE IN HYDROGEN GAS AND DETERMINATION IN THE PROTON’S PSEUDOSCALAR COUPLING g P PNPI participants in MuCAP collaboration*) :

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Стандартная Модель и структура нуклонов G v = 0.9755 ± 0.0005 G a = 1.245 ± 0.003

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  1. PRECISION MEASUREMENT OF THE RATE OF MUON CAPTURE IN HYDROGEN GAS AND DETERMINATION IN THE PROTON’S PSEUDOSCALAR COUPLING gP PNPI participants in MuCAP collaboration*) : V.A. Andreev, V.A. Ganzha, P. A.Kravtsov, A.G. Krivshich, M.P. Levchenko, E.M. Maev, O.E. Maev, G.E. Petrov, G.N. Schapkin, G.G. Semenchuk, M. A. Soroka, A.A. Vasilyev, A.A. Vorobyov, M.E. Vznuzdaev

  2. Стандартная Модель и структура нуклонов • Gv = 0.9755 ± 0.0005 • Ga = 1.245 ± 0.003 • Gm = 3.582 ± 0.003 Gp(th) = 8.26 ± 0.23 • Gp = 6 – 12 • Gp (RMC) = 12.2 ± 0.9 ± 0.4

  3. 1 % LH2 100% LH2 pm ppμ ppmO • λpd ~ 1.4x1010 s-1, λppμ ~ 1.9-2.7x106 s-1 • λμz ~ 5x1010 s-1 ppμ pm ppmO ppmP ppmP time (ms) LT = 12 s-1 triplet (F=1) pμ↑↑ Lortho=506s-1 Lpara=200s-1 λop μ ppμ ppμ f λppm ortho (J=1) para (J=0) pμ↑↓ singlet (F=0) LS= 691s-1 n+n

  4. Стратегия MuCap эксперимента • Измерение времени жизни - с точностью 10ppm, регистрация 1010m→ennраспадов S = 1/- - 1/+~ 1% • Однозначность интерпретации захват из F=0 состоянияmp атома приплотности LH2 1% • Использование методики активной мишени (TPC) с точной регистрацией координат и времени остановок мюонов, реконструкция треков электронов к точке распада • Использование ультрачистого водородаСz < 10-8 • Контроль примесей по реакциям:mp + Z mZ+ p, ~10 ppb N2 • Обеспечение изотопической чистоты водорода mp + d md+ p + 134 eV, примесь D2~1 ppm, диффузияmd ~cm

  5. IV. the new protium isotope separation facility:production of ultra-depleted protium 1) sample #74 from column after separation run: cd < 0.14 ppm (twice analyzed April-15 & May-18)2) 3 stp-ltr protium sample from run-10 gas cd < 0.07 ppm3) 0.5 stp-ltr sample with end-of-run-8 gas cd = 1.44±0.13 ppm

  6. Ortho-Para Hydrogen Chromatogram (Natural hydrogen, Column pressure = 1.2 bar; Reboiler power = 10W) Para Ortho

  7. Beamline Kicker Plates m detector m- TPC +12.5 kV -12.5 kV 50 ns switching time • Single muon requirement (to prevent systematics from pile-up) • limits accepted m rate to ~ 7 kHz, • while PSI beam can provide ~ 70 kHz • Muon-On-Demand concept • Muon-On-Demand concept mLan kickerTRIUMF rf design 2-Dec-2005 kicked Fig will be improved dc ~3 times higher rate

  8. Histogram shows dramatic accidental suppression in the lifetime spectrum due to m-e impact parameter cuts (cut radius given in the legend).

  9. Общая набранная статистика Общий объем данных за 2006-2007 гг. ~ 40 Tb Анализ одного файла данных размером 1.6 Gb занимает примерно 1 час процессорного времени. На данный момент в ПИЯФе есть 1Tb данных за 2006-2007 года. Анализ этих данных потребует ~ 600 часов!!!!!

  10. Результаты анализа данных за 2004 год • = 1.6 х 109 • λμ+ = 455162.2 ± 4.4 s-1 (μLAN experiment, to be published) • λμ- = 455851.4 ± 12.5stat ± 8.5syst s-1 (MuCAP 2004) • ΛSMuCap = 725.0 ± 13.7stat ± 10.7syst s-1 • ΛSTh = 691.2 s-1(averaged) + 19.4s-1(radiation correction) • gPMuCap = gPTh + (dgP/dΛS) x (ΛSMuCap - ΛSTh) = 7.3±1.1(15%) • gPTh = 8.26 ± 0.23 (2.8%)

  11. Earlier, in 1998, we have studied the muon capture on 3He. The muon capture rate in the channel μ- + 3He → 3H + νμ was measured with high precision : Λc = 1496.0 ± 4.0 s-1. This result have been used in some theoretical analyses (T.Gorringe and H.W.Fearing, 2004) for deriving the proton’s pseudoscalar coupling gP. They applied the microscopic theory based on impulse approximation supplemented by explicit calculations of the meson exchange corrections . Their result was gP = 8.77 ± 1.58.

  12. Публикации в 2007 году по теме «Мюон» V.A. Andreev, T.I. Banks et al. “ Measurement of the Rate of Muon Capture in Hydrogen Gas and Determination of the Proton's Pseudoscalar Coupling gP.” Phys.Rev.Lett. 99, 032002 (2007) V.A. Ganzha, P.A. Kravtsov et al. “A Circulating Hydrogen Ultra-High Purification System for the MuCap Experiment” Nucl. Instr. Methods Phys. Res. A 578 (2007) 485-497

  13. ФИНАНСЫ 2007 • Тема РАН – 400 т.руб + 550 т.руб • Грант CRDF~49 K USD

  14. ГРУППА МЕЗОЯДЕРНЫХ РЕАКЦИЙ Вед.н.с. к.н. - Семенчук Г.Г. Ст.н.с. к.н. - Маев Е.М. Ст.н.с. - Петров Г.Е. Cт.н.с. к.н. - Воропаев Н.И. Н.с. - Балин Д.В. Н.с. - Смиренин Ю.В. Н.с. - Маев О.Е. Инж. пр. - Фотиева Е.В. Инж.оп.пр. - Дубограй B.C. Монт. р/а - Еремеев А.Д.

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