547 research outputs found
A Flexible Simple Thermostat for Small Objects and the Range of 100 to 400 K
A flexible, inexpensive thermostat for the temperature range 100 to 400 K is described. Liquid nitrogen is the coolant and a gas serves as transfer medium. The temperature can be set to better than 1 K and is held there within (1/2) K by an electronic control system. The relatively small working volume of the order of 10 cm^3 allows quick changes of temperature, a desirable feature in typical semiconductor experiments
A flexible, simple thermostat for small objects and the temperature range of 100 deg K to 400 deg K
Thermostat for small objects with temperature range of 100 to 400
Noise and Equivalent Circuit of Double Injection
Measurements of the highâfrequency noise of a silicon doubleâinjection diode result in ăi^2ă = αâ
4kT(1/r)Îf with α=1.04 and in agreement with the literature. A new interpretation demands Nyquist noise with αâĄ1 in these devices at high frequencies. This is in accord with an equivalent circuit derived for the doubleâinjection process. Speculations are made on the general validity of Nyquist noise in nonlinear devices at high frequencies. In addition, generationârecombination noise is suggested as the prime source of the lowâfrequency noise
Collision damping in the pi 3He -> d'N reaction near the threshold
We present a simple quantum mechanical model exploiting the optical potential
approach for the description of collision damping in the reaction pi 3He -> d'N
near the threshold, which recently has been measured at TRIUMF. The influence
of the open d'N -> NNN channel is taken into account. It leads to a suppression
factor of about ten in the d' survival probability. Applications of the method
to other reactions are outlined.Comment: RevTeX4, 14 pages, 3 Postscript figures, uses epsfig.sty, to appear
in Phys.Rev.
Search for Exotic Muon Decays
Recently, it has been proposed that the observed anomaly in the time
distribution of neutrino induced reactions, reported by the KARMEN
collaboration, can be interpreted as a signal from an exotic muon decay branch
mu+ to e+ X. It has been shown that this hypothesis gives an acceptable fit to
the KARMEN data if the boson X has a mass of m_X=103.9MeV/c^2, close to the
kinematical limit. We have performed a search for the X particle by studying
for the first time the very low energy part of the Michel spectrum in mu+
decays. Using a HPGe detector setup at the muE4 beamline at PSI we find
branching ratios BR(mu+ to e+ X)<5.7e-4 (90% C.L.) for most of the region
103MeV/c^2<m_X<105MeV/c^2.Comment: 9 page
Does the quark cluster model predict any isospin two dibaryon resonance?
We analyze the possible existence of a resonance in the channel
with isospin two by means of nucleon- interactions based on the
constituent quark model. We solve the bound state and the scattering problem
using two different potentials, a local and a non-local one. The non-local
potential results to be the more attractive, although not enough to generate
the experimentally predicted resonance.Comment: 9 pages in Latex (revtex), 2 eps figures available under reques
Quark Cluster Model Study of Isospin-Two Dibaryons
Based on a quark cluster model for the non-strange sector that reproduces
reasonably well the nucleon-nucleon system and the excitation of the
isobar, we generate a nucleon- interaction and present the predictions
for the several isospin two channels. The only attractive channels are
and , but not attractive enough to generate a resonance. If a resonance is
artificially generated and is required to have the observed experimental mass,
then our model predicts a width that agrees with the experimental result.Comment: 12 pages, 5 poscript figures available under request. To appear in
Phys. Rev.
Three-body decay of the d* dibaryon
Under certain circumstances, a three-body decay width can be approximated by
an integral involving a product of two off-shell two-body decay widths. This
``angle-average'' approximation is used to calculate the decay width
of the dibaryon in a simple model for the most
important Feynman diagrams describing pion emissions with baryon-baryon recoil
and meson retardation. The decay width is found to be about 0.006 (0.07, 0.5)
MeV at the mass of 2065 (2100, 2150) MeV for input dynamics derived from
the Full Bonn potential. The smallness of this width is qualitatively
understood as the result of the three-body decay being ``third forbidden''. The
concept of forbiddenness and the threshold behavior of a three-body
decay are further studied in connection with the decay of the dibaryon
where the idea of unfavorness has to be introduced.
The implications of these results are briefly discussed.Comment: 15 pages, RevTeX, two-column journal style, six figure
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