The MuCap experiment at the Paul Scherrer Institute has measured the rate Λ(S) 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. Λ(S) 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 ± 5.4(stat) ± 5.1(syst)) s(-1) and derive the proton's pseudoscalar coupling g(P)(q(0)(2) = -0.88 m(μ)(2)) = 8.06 ± 0.55.
The nuclear
dd
-fusion reaction can proceed by three possible channels:
,
,
. Interest in
dd
-fusion has been aroused by both fundamental research and astrophysics and applied science, particularly ...in the field of fusion reactor development. In the 1970s, the idea of studying the nuclear
dd
-fusion reaction using polarized deuteron beams was proposed at the Kurchatov Institute. The development of this idea was continued in the PolFusion (polarized fusion) nuclear physics experiment, which aims at studying the reaction of nuclear
dd
synthesis with polarized source particles in the low energy region. The experiment is planned to measured the scattering asymmetries of
dd
-fusion reaction products in the final state at different mutual orientation of the spins of colliding deuterons in the energy range 10–100 keV. The authors present an overview of the status of the experiment.
The rate of nuclear muon capture by the proton has been measured using a new technique based on a time projection chamber operating in ultraclean, deuterium-depleted hydrogen gas, which is key to ...avoiding uncertainties from muonic molecule formation. The capture rate from the hyperfine singlet ground state of the microp atom was obtained from the difference between the micro(-) disappearance rate in hydrogen and the world average for the micro(+) decay rate, yielding Lambda(S)=725.0+/-17.4 s(-1), from which the induced pseudoscalar coupling of the nucleon, g(P)(q(2)=-0.88m(2)(micro))=7.3+/-1.1, is extracted.
Search for Muon Catalyzed 3Hed Fusion Fotev, V. D.; Ganzha, V. A.; Ivshin, K. A. ...
Physics of particles and nuclei,
06/2024, Letnik:
55, Številka:
3
Journal Article
Recenzirano
—This report presents the results of an experiment aimed at observation of the muon catalyzed
3
He
d
fusion reaction
3
He +
(3.66 MeV) +
p
(14.64 MeV) + μ which might occur after a negative muon stop ...in the D
2
+
3
He gas mixture. The basic element of the experimental setup is a Time Projection Chamber (TPC) which can detect the incoming muons and the products of the fusion reaction. The TPC operated with the D
2
+
3
He (5%) gas mixture at 31 K temperature. About
3
Heμ
d
molecules were produced with only 2 registered candidates for the muon catalyzed
3
He
d
fusion with the expected background
events. This gives an upper limit for the probability of the fusion decay of the
3
Heμ
d
molecule
at 90% C.L. Also presented are the measured formation rate of the
3
Heμ
d
molecule
and the probability of the fast muon transfer from the excited to the ground state of the
atom
. The obtained results are compared with the previously published data.
We present results for three charmonia states (ψ′, χc, and J/ψ) in d+Au collisions at |y|<0.35 and sNN−−−√=200 GeV. We find that the modification of the ψ′ yield relative to that of the J/ψ scales ...approximately with charged particle multiplicity at midrapidity across p+A, d+Au, and A+A results from the Super Proton Synchrotron and the Relativistic Heavy Ion Collider. In large-impact-parameter collisions we observe a similar suppression for the ψ′ and J/ψ, while in small-impact-parameter collisions the more weakly bound ψ′ is more strongly suppressed. Owing to the short time spent traversing the Au nucleus, the larger ψ′ suppression in central events is not explained by an increase of the nuclear absorption owing to meson formation time effects.
The MuCap experiment at the Paul Scherrer Institute has measured the rate Λ{sub S} 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. Λ{sub S} is determined from the difference between the μ{sup -} disappearance rate in hydrogen and the free muon decay rate. The result is based on the analysis of 1.2×10{sup 10} μ{sup -} decays, from which we extract the capture rate Λ{sub S} =(714.9±5.4{sub stat} ±5.1{sub syst} )s{sup -1} and derive the proton’s pseudoscalar coupling g{sub P} (q{sup 2}{sub 0} =-0.88m{sup 2}{sub μ} )=8.06±0.55 .
We present results for three charmonia states (psi' chi(c), and J/ psi) in d + Au collisions at vertical bar y vertical bar < 0.35 and root s(NN) = 200 GeV. We find that the modification of the psi' ...yield relative to that of the J/ psi scales approximately with charged particle multiplicity at midrapidity across p + A, d + Au, and A + A results from the Super Proton Synchrotron and the Relativistic Heavy Ion Collider. In large-impact-parameter collisions we observe a similar suppression for the psi' and J/ psi, while in small-impact-parameter collisions the more weakly bound psi' is more strongly suppressed. Owing to the short time spent traversing the Au nucleus, the larger psi' suppression in central events is not explained by an increase of the nuclear absorption owing to meson formation time effects.
A 64-channel readout and data-acquisition module is described in detail. It consists of an H12700 multianode photomultiplier tube, four PADIWA preamplifier boards, and a TRB v3 card that perform the ...functions of a time-to-digital converter and a data concentrator. The software modules that are necessary for operation of the prototype are described. The inter-channel delays are calibrated. The drift of individual delays does not exceed 0.5 ns for the entire measurement time. The spectra of the “time over threshold” (ToT) are investigated. The influence of periodic noise pickups and the need to improve circuit designs are revealed. The timing properties of the wavelength shifter and its effect on the detection efficiency for Cherenkov rings are investigated. The most intense component is characterized by a decay time of 1.1 ns and there are components with characteristic times of 3.8 and 45 ns. The influence of single-electron spectrum features on the detection efficiency for photoelectrons and the probability of false hits are determined. The total time resolution of 131 channels is 1.1 ns (FWHM). The results make it possible to use the investigated system of readout and data acquisition in the CBM experiment. Nevertheless, the elimination of the revealed shortcomings will provide the efficiency margin and improve the reliability of the system during long-term operation.
Measurements of neutral pion (pi(0)) production at midrapidity in root s(NN)=200 GeV Au+Au collisions as a function of transverse momentum, p(T), collision centrality, and angle with respect to ...reaction plane are presented. The data represent the final pi(0) results from the PHENIX experiment for the first RHIC Au+Au run at design center-of-mass energy. They include additional data obtained using the PHENIX Level-2 trigger with more than a factor of 3 increase in statistics over previously published results for p(T)>6 GeV/c. We evaluate the suppression in the yield of high-p(T) pi(0)'s relative to pointlike scaling expectations using the nuclear modification factor R-AA. We present the p(T) dependence of R-AA for nine bins in collision centrality. We separately integrate R-AA over larger p(T) bins to show more precisely the centrality dependence of the high-p(T) suppression. We then evaluate the dependence of the high-p(T) suppression on the emission angle Delta phi of the pions with respect to event reaction plane for seven bins in collision centrality. We show that the yields of high-p(T) pi(0)'s vary strongly with Delta phi, consistent with prior measurements 1,2. We show that this variation persists in the most peripheral bin accessible in this analysis. For the peripheral bins we observe no suppression for neutral pions produced aligned with the reaction plane, whereas the yield of pi(0)'s produced perpendicular to the reaction plane is suppressed by a factor of similar to 2. We analyze the combined centrality and Delta phi dependence of the pi(0) suppression in different p(T) bins using different possible descriptions of parton energy loss dependence on jet path-length averages to determine whether a single geometric picture can explain the observed suppression pattern.
The rate of nuclear muon capture by the proton has been measured using a new technique based on a time projection chamber operating in ultraclean, deuterium-depleted hydrogen gas, which is key to ...avoiding uncertainties from muonic molecule formation. The capture rate from the hyperfine singlet ground state of the {mu}p atom was obtained from the difference between the {mu}{sup -} disappearance rate in hydrogen and the world average for the {mu}{sup +} decay rate, yielding {lambda}{sub S}=725.0{+-}17.4 s{sup -1}, from which the induced pseudoscalar coupling of the nucleon, g{sub P}(q{sup 2}=-0.88m{sub {mu}}{sup 2})=7.3{+-}1.1, is extracted.
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