239 research outputs found
Modelling water infiltration into macroporous hill slopes using special boundary conditions
The formulation of suitable boundary conditions is a very crucial task when
modeling water infiltration into macroporous hill slopes. The processes of water infiltration
and exfiltration vary in space and time and depend on the flow on the surface as well as in the
subsurface. In this contribution we have purposed special system process dependent boundary
conditions can be formulated for a two-phase dual-permeability model to simulate infiltration
and exfiltration processes. The presented formulation analyses the saturation conditions of the
dual-permeability model (e.g. saturation) at the boundary nodes and adopts the boundary
conditions depending on the processes at the soil surface such as rainfall intensity. Using a
simplified macroporous hill slope and a heavy rainfall event we demonstrate the functionality
of our formulation
Muon Catalyzed Fusion in 3 K Solid Deuterium
Muon catalyzed fusion in deuterium has traditionally been studied in gaseous
and liquid targets. The TRIUMF solid-hydrogen-layer target system has been used
to study the fusion reaction rates in the solid phase of D_2 at a target
temperature of 3 K. Products of two distinct branches of the reaction were
observed; neutrons by a liquid organic scintillator, and protons by a silicon
detector located inside the target system. The effective molecular formation
rate from the upper hyperfine state of and the hyperfine transition
rate have been measured: , and .
The molecular formation rate is consistent with other recent measurements, but
not with the theory for isolated molecules. The discrepancy may be due to
incomplete thermalization, an effect which was investigated by Monte Carlo
calculations. Information on branching ratio parameters for the s and p wave
d+d nuclear interaction has been extracted.Comment: 19 pages, 11 figures, submitted to PRA Feb 20, 199
Measurement of the Resonant Molecular Formation Rate in Solid HD
Measurements of muon-catalyzed dt fusion () in solid
HD have been performed. The theory describing the energy dependent resonant
molecular formation rate for the reaction + HD is
compared to experimental results in a pure solid HD target. Constraints on the
rates are inferred through the use of a Monte Carlo model developed
specifically for the experiment. From the time-of- flight analysis of fusion
events in 16 and 37 targets, an average formation rate
consistent with 0.897(0.046) (0.166) times the
theoretical prediction was obtained.Comment: 4 pages, 5 figure
Steps towards the hyperfine splitting measurement of the muonic hydrogen ground state: pulsed muon beam and detection system characterization
The high precision measurement of the hyperfine splitting of the
muonic-hydrogen atom ground state with pulsed and intense muon beam requires
careful technological choices both in the construction of a gas target and of
the detectors. In June 2014, the pressurized gas target of the FAMU experiment
was exposed to the low energy pulsed muon beam at the RIKEN RAL muon facility.
The objectives of the test were the characterization of the target, the
hodoscope and the X-ray detectors. The apparatus consisted of a beam hodoscope
and X-rays detectors made with high purity Germanium and Lanthanum Bromide
crystals. In this paper the experimental setup is described and the results of
the detector characterization are presented.Comment: 22 pages, 14 figures, published and open access on JINS
Theory of muonic hydrogen - muonic deuterium isotope shift
We calculate the corrections of orders alpha^3, alpha^4 and alpha^5 to the
Lamb shift of the 1S and 2S energy levels of muonic hydrogen (mu p) and muonic
deuterium (mu d). The nuclear structure effects are taken into account in terms
of the proton r_p and deuteron r_d charge radii for the one-photon interaction
and by means of the proton and deuteron electromagnetic form factors in the
case of one-loop amplitudes. The obtained numerical value of the isotope shift
(mu d) - (mu p) for the splitting (1S-2S) 101003.3495 meV can be considered as
a reliable estimation for corresponding experiment with the accuracy 10^{-6}.
The fine structure interval E(1S)-8E(2S) in muonic hydrogen and muonic
deuterium are calculated.Comment: 22 pages, 7 figure
Proton Zemach radius from measurements of the hyperfine splitting of hydrogen and muonic hydrogen
While measurements of the hyperfine structure of hydrogen-like atoms are
traditionally regarded as test of bound-state QED, we assume that theoretical
QED predictions are accurate and discuss the information about the
electromagnetic structure of protons that could be extracted from the
experimental values of the ground state hyperfine splitting in hydrogen and
muonic hydrogen. Using recent theoretical results on the proton polarizability
effects and the experimental hydrogen hyperfine splitting we obtain for the
Zemach radius of the proton the value 1.040(16) fm. We compare it to the
various theoretical estimates the uncertainty of which is shown to be larger
that 0.016 fm. This point of view gives quite convincing arguments in support
of projects to measure the hyperfine splitting of muonic hydrogen.Comment: Submitted to Phys. Rev.
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