An
n
n
Λ
, which consists of two neutrons and a Lambda hyperon, is a multi-baryon system with no charge. Studying the
n
n
Λ
state would provide information about the
Λ
n
interaction which has not ...been directly measured by a scattering experiment. The experiment (E12-17-003) was performed in order to search for the
n
n
Λ
state at Jefferson Lab. The
n
n
Λ
is expected to be produced by the
(
e
,
e
′
K
+
)
reaction, which has sensitivity to both bound and resonance states if the natural width of the
n
n
Λ
is narrow enough to be observed as a peak. The experiment used gas targets of hydrogen and tritium for mass calibration and the
n
n
Λ
production, respectively. The mass calibration with
H
(
e
,
e
′
K
+
)
Λ
/
Σ
0
reactions gave the mass resolution of the
Λ
and
Σ
0
each 3.5
MeV
/
c
2
FWHM, for the elementary reaction. A spectrum of
3
H
(
e
,
e
′
K
+
)
X
was obtained, and a simple model with a
Λ
n
final state interaction was applied to reproduce the spectrum.
In this work, the thermal elastohydrodynamic lubrication (TEHL) in an impact motion is explored using multigrid (MG) method and column by column scanning techniques. A steel ball impacts onto an ...infinite steel plane lubricated with a thin layer of oil. The study starts from a smooth contact problem and the results are compared with the corresponding isothermal ones. Then surface waviness is imposed on the steel ball surface to check the fluctuation in the oil film.
Pressure, film thickness and mid-layer temperature profiles in X-direction with surface waviness, hoil=10μm, h0⁎=0.5mm, A=0.5μm, L =100μm. (a) Pressure. (b) Film thickness. (c) Temperature. Display omitted
•A mathematical model is built describing thermal EHL phenomenon in a impact-rebound process.•The plane surface is lubricated with a layer of Newtonian lubricant.•In an impact problem, the larger the initial impact gap, the larger the thermal rise.•Surface waviness fluctuates film thickness obviously but pressure and temperature slightly.•Future work will focus on the influence of a rheological model.
We investigate the
γ
d
→
d
π
+
π
-
reaction for a study of a possible
N
Δ
dibaryon state using a deuterium target with a magnetic spectrometer, Neutral Kaon Spectrometer 2 (NKS2), at Research Center ...for Electron Photon Science (ELPH), Tohoku University. The incident photon energy ranged from 0.78 to 1.08 GeV. Resonance-like structures were found at a mass of
∼
2.15
GeV
/
c
2
with a width of
∼
0.1
GeV
/
c
2
in the
d
π
+
and
d
π
-
invariant mass spectra.
Abstract
A high-precision hypernuclear experiment has been performed at the Mainz Microtron (MAMI) to determine the hypertriton Λ binding energy via decay-pion spectroscopy. A key element of this ...measurement is an accurate calibration of the magnetic spectrometers with the MAMI beam. For such an absolute calibration with small statistical and systematic uncertainties the undulator light interference method will be applied. In this contribution the basic principle of this method is discussed and the analysis status of the measured synchrotron radiation spectra is presented.
A novel interferometric method is presented for the measurement of the absolute energy of electron beams. In the year 2016, a pioneering experiment was performed using a 195 MeV beam of the Mainz ...Microtron (MAMI). The experimental setup consisted of two collinear magnetic undulators as sources of coherent optical synchrotron light and a high-resolving grating monochromator. Beam energy measurements required the variation of the relative undulator distance in the decimeter range and the analysis of the intensity oscillation length in the interference spectrum. A statistical precision of 1 keV was achieved in 1 h of data taking, while systematic uncertainties of 700 keV were present in the experiment. These developments aim for a relative precision of 10−5 in the absolute momentum calibrations of spectrometers and high-precision hypernuclear experiments. Other electron accelerators with beam energies in this regime such as the Mainz Energy Recovering Superconducting Accelerator (MESA) might benefit from this new method.
Abstract
Isothermal elastohydrodynamic lubrication (EHL) theory has brought the improvement in function, performance, and durability of machine elements with concentrated contacts. The main reason is ...that the theory can evaluate the lubrication characteristics, such as film thickness and pressure distributions, from the shape and size of contacting materials, lubricant viscosity at the entrance to the EHL conjunction, entrainment velocity, equivalent elastic modulus, and applied load. However, in order to estimate the film thickness and pressure distributions more accurately and to make clear the traction behaviour based on lubricant rheology, it is necessary to establish thermal EHL theory, which incorporates heat generation in the fluid film and heat transfer in the machine system on the foundation of isothermal EHL theory. The thermal conductivity of contact materials controls temperature in the fluid film and consequently the lubricant viscosity. Therefore, the EHL characteristics are affected remarkably by the thermal conductivity of contact materials. In this article, the effects of the thermal conductivity of contacting materials on the film thickness, pressure, and traction coefficient are described.
This paper is focused on the effect of impact loading on micro-deformation of asperities in elliptical elastohydrodynamic contacts. Based upon isothermal Newtonian numerical analyses, it is ...elucidated that a micro-groove, which appears in the ridge under impact loading in elliptical contacts, is brought about by two different mechanisms. One is the smooth surface local pressure difference across the virtual ridge and the other is the macroscopic pressure difference along the ridge. The formation of the micro-groove due to the former mechanism is influenced by the shape, size and orientation of the ridge, and the smooth surface pressure distribution depending on the initial impact gap and loading speed, and that due to the latter is markedly influenced by the loading speed.
► Effect of impact loading on micro-deformation of asperities in elliptical EHL contacts is disclosed. ► The high pressure produces the micro-groove in ridges. ► The micro-groove is formed by two different mechanisms. ► Effects of ridge size, shape and orientation, initial impact gap and loading speed on the micro-groove formation are elucidated.
The behavior of point contact elastohydrodynamic lubrication (EHL) films under pure rolling short stroke reciprocating motion is investigated using both optical interferometry technique and ...theoretical analysis. The EHL films are recorded with a high-speed color camera and simulated with multigrid techniques. General variation of oil film under point contact reciprocating motion is explained by a comparison between a fully flooded simulation and an experiment with a frequency of 7.78
Hz. Influence of starvation is considered by another simulation under a higher working frequency of 14.4
Hz and the simulated results are compared with experimental results. Both simulations show good agreements quantitatively with experiments. In addition, general tribo-characteristics of EHL under fully flooded and starved conditions are discussed.
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