Muon Capture in Hyperfine States of 11B Muonic Atom (original) (raw)
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Muon Capture in 11B Muonic Atom and Hyperfine Spin Dependence
Progress of Theoretical Physics, 1984
Total muon capture rates are studied theoretically for the hyperfine states of the llB muonic atom. The final nuclear states are described by the continuum-neutron model, where one neutron is in the continuum with the residual nucleus lOBe. The theoretical values of the muon capture rate for the F= 1 state are in fairly good agreement with the recent experimental data obtained by Tokyo group, while those for the F= 2 state are about a half of the experimental data. The ratio of the total muon capture rates from hyperfine states is rather insensitive to the nuclear model in our framework and to the pseudoscalar coupling constant versus axial vector one, gpl gAo A similar ratio of the partial muon capture rates leading to the bound state of 1/2-'is strongly dependent on gp/gA.
A precision measurement of nuclear muon capture on 3He
Physics Letters B, 1998
The muon capture rate in the reaction µ − + 3 He → ν µ + 3 H has been measured at PSI using a modular high pressure ionization chamber. The rate corresponding to statistical hyperfine population of the µ 3 He atom is (1496.0±4.0) s −1 . This result confirms the PCAC prediction for the pseudoscalar form factors of the 3 He -3 H system and the nucleon. PACS: 23.40.-s * This paper is part of the thesis works of W. Prymas and N.I. Voropaev
Physical Review Letters, 2013
The MuCap experiment at the Paul Scherrer Institute has measured the rate ΛS of muon capture from the singlet state of the muonic hydrogen atom to a precision of 1 %. A muon beam was stopped in a time projection chamber filled with 10-bar, ultrapure hydrogen gas. Cylindrical wire chambers and a segmented scintillator barrel detected electrons from muon decay. ΛS is determined from the difference between the µ − disappearance rate in hydrogen and the free muon decay rate. The result is based on the analysis of 1.2 × 10 10 µ − decays, from which we extract the capture rate Λ S = (714.9 ± 5.4stat ± 5.1syst) s −1 and derive the proton's pseudoscalar coupling g P (q 2 0 = −0.88 m 2 µ ) = 8.06 ± 0.55.
Precision measurement of nuclear muon capture by3He
Hyperfine Interactions, 1996
The muon capture rate in the reaction µ − + 3 He → ν µ + 3 H has been measured at PSI using a modular high pressure ionization chamber. The rate corresponding to statistical hyperfine population of the µ 3 He atom is (1496.0±4.0) s −1 . This result confirms the PCAC prediction for the pseudoscalar form factors of the 3 He -3 H system and the nucleon. PACS: 23.40.-s * This paper is part of the thesis works of W. Prymas and N.I. Voropaev
Physical Review Letters, 2007
The rate of nuclear muon capture by the proton has been measured using a new experimental technique based on a time projection chamber operating in ultra-clean, deuterium-depleted hydrogen gas at 1 MPa pressure. The capture rate was obtained from the difference between the measured µ − disappearance rate in hydrogen and the world average for the µ + decay rate. The target's low gas density of 1% compared to liquid hydrogen is key to avoiding uncertainties that arise from the formation of muonic molecules. The capture rate from the hyperfine singlet ground state of the µp atom is measured to be Λ S = 725.0 ± 17.4 s −1 , from which the induced pseudoscalar coupling of the nucleon, g P (q 2 = −0.88 m 2 µ ) = 7.3 ± 1.1, is extracted. This result is consistent with theoretical predictions for g P that are based on the approximate chiral symmetry of QCD.
Radiative muon capture and induced pseudoscalar coupling constant in nuclear matter
Journal of Physics G: Nuclear and Particle Physics, 2003
The recent TRIUMF experiment for µ − p → nν µ γ gave a surprising result that the induced pseudoscalar coupling constant g P was larger than the value obtained from µ − p → nν µ experiment as much as 44 %. Reexamining contribution of the axial vector current in electromagnetic interaction, we found an additional term to the matrix element which was used to extract the g P value from the measured photon energy spectrum. This additional term, which plays a key role to restore the reliability of g P (−0.88m 2 µ) = 6.77g A (0), is shown to affect the g P quenching problems in nucleus.
Muon capture by oriented nuclei: new possibilities for studying induced pseudoscalar interaction
Physics of Atomic Nuclei
Angular distribution of neutrinos (recoil nucleus) in muon capture for an allowed Gamov-Teller transition is considered by taking account of hyperfine effects. This angular distribution is shown to include a correlation of the form P_2(cos A), where A is the angle between the neutrino momentum and the axis specifying the orientation of the initial mesic atom. This correlation, which arises only if the initial mesic atom is aligned, proves highly sensitive to the form factor g_P of induced pseudoscalar interaction. The proposed method for determinating g_P may be realized for the transition 1+ to 2+ from the ground state of the 6-Li nucleus to the narrow resonance of the 6-He nucleus in continuum, as well as in the processes like 10-B(3+) to 10-Be(2+), 11-B(3/2-) to 11-Be(1/2-), 23-Na(3/2+) to 23-Ne(1/2+) with transitions to bound states.
Induced Pseudoscalar Coupling in Muon Capture and Second-Order Corrections
1999
The hyperfine effect in muon capture rate is analyzed with taking into account of the second-order terms in 1/M in the non-relativistic Hamiltonian. It is shown that in the situation of the dominance of the squared first-order terms the interference of zero-order and second-order terms has no significant influence. General expression for neutrino (recoil nucleus) angular distribution in muon capture by nucleus with non-zero spin is proposed. High sensitivity to gPg_PgP of the term related with alignment of the initial mesic atom is discussed in the approximation of dominating Gamow--Teller matrix element.
Muon capture in16O and nuclear coexistence
Lettere Al Nuovo Cimento Series 2, 1973
The purpose of this paper is to show that the nuclear shape coexistence can resolve most of the experimental-theoretical discrepancies for muon capture on ~sO. The muon capture is a weak-interaction process where a muon (,~-) from the atomic orbit is captured by a proton in the nucleus converting it into a neutron, and a muon neutrino (v~) is emitted. The final nucleus may be left in an excited state or in the ground state. There are two approaches that are usually taken. The first is to use the muon capture process to extract information about the weak-interaction constants. This is usually done in a model-independent way for the nuclear part. The second approach (1) is to assume that the weak-interaction part of the process is known better than the nuclearstructure part and use the ~-capture process for obtaining information about the nuclear wave functions. In this letter, we will take the second point of view. The previous studies of muon capture have shown that the first forbidden nuclear transitions (L = 1) dominate the capture process for closed-shell N= Z nuclei (2). Thus the states which are strongly
Muon capture in hydrogen and deuterium
Hyperfine Interactions, 2009
We report on a new generation of muon lifetime experiments at PSI to measure the nuclear muon capture rate in hydrogen and deuterium with ≤1% accuracy. The goals are to determine in μp capture the induced pseudoscalar coupling g P predicted in HBchPT, and in μd capture the axial two-body current term L 1A described by modern EFT's. For the μp experiment a hydrogen TPC was developed as active muon stop detector, surrounded by cylindrical wire chambers and a plastic hodoscope as electron detector. Ultra-high purity of the hydrogen isotope 1 H 1 at levels below 10 −8 was achieved with a specially developed gas circulation and purification system, and with a novel isotope separation column. About 2 • 10 10 events were collected which are now in final analysis. Data from the first production run result in g P = 7.3 ± 1.1 in good agreement with theory. The μd experiment is in development. It requires measurements in ultra-pure, cold deuterium gas at ∼30K. For this we are constructing a new Cryo-TPC.