3,492 research outputs found
Matter radii of light halo nuclei
We re-examine the matter radii of diffuse halo nuclei, as deduced from
reaction cross section measurements at high energy. Careful consideration is
given to the intrinsic few-body structure of these projectiles and the
adiabatic nature of the projectile-target interaction. Using Li,
Be and B as examples we show that data require significantly
larger matter radii than previously reported. The revised value for Li
of 3.55 fm is consistent with three-body models with significant -intruder
state components, which reproduce experimental Li momentum distributions
following Li breakup, but were hitherto thought to be at variance with
cross section data.Comment: 8 pages RevTeX plus 5 Postscript figures. Figures also available at
http://www.ph.surrey.ac.uk/scnp/jakpub/figures.html Scheduled tentatively for
13May96 issue of Phys. Rev. Let
Non-adiabatic corrections to elastic scattering of halo nuclei
We derive the formalism for the leading order corrections to the adiabatic
approximation to the scattering of composite projectiles. Assuming a two-body
projectile of core plus loosely-bound valence particle and a model (the core
recoil model) in which the interaction of the valence particle and the target
can be neglected, we derive the non-adiabatic correction terms both exactly,
using a partial wave analysis, and using the eikonal approximation. Along with
the expected energy dependence of the corrections, there is also a strong
dependence on the valence-to-core mass ratio and on the strength of the
imaginary potential for the core-target interaction, which relates to
absorption of the core in its scattering by the target. The strength and
diffuseness of the core-target potential also determine the size of the
corrections. The first order non-adiabatic corrections were found to be smaller
than qualitative estimates would expect. The large absorption associated with
the core-target interaction in such halo nuclei as Be11 kills off most of the
non-adiabatic corrections. We give an improved estimate for the range of
validity of the adiabatic approximation when the valence-target interaction is
neglected, which includes the effect of core absorption. Some consideration was
given to the validity of the eikonal approximation in our calculations.Comment: 14 pages with 10 figures, REVTeX4, AMS-LaTeX v2.13, submitted to
Phys. Rev.
Quantum variational measurement in the next generation gravitational-wave detectors
A relatively simple method of overcoming the Standard Quantum Limit in the
next-generation Advanced LIGO gravitational wave detector is considered. It is
based on the quantum variational measurement with a single short (a few tens of
meters) filter cavity. Estimates show that this method allows to reduce the
radiation pressure noise at low frequencies () to the level
comparable with or smaller than the low-frequency noises of non-quantum origin
(mirrors suspension noise, mirrors internal thermal noise, and gravity
gradients fluctuations).Comment: 12 pages, 4 figures; NSNS SNR estimates added; misprints correcte
A Domestic Disturbance: The Seventh Circuit Encroaches on Foreign Related Party Transactions
Has deference to administrative regulation gone too far in its impact on American corporations and consequently become to great a foe to American corporations in a global marketplace? In the wake of the widespread corporate scandals, many of the regulations enacted are aimed at combating corporate fraud. Recently, in Square D Co. v. Commissioner of the Internal Revenue Service, the Seventh Circuit Court of Appeals upheld the validity of one such regulation, requiring taxpayers to utilize the cash basis method of accounting to deduct interest payments made to tax-exempt foreign related parties. This Note examines where this regulation fits with other similarly aimed provisions;the Seventh Circuit’s rationale for upholding this regulation;arguments for a more narrow construction of the power allocated to the Secretary of the Treasury;and concludes that, based on the overarching purpose of preventing corporate fraud, the Seventh Circuit’s decision was correct in substance but was overly deferential to administrative regulation and ignored many compelling arguments that support its decision
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