185 research outputs found
Measurements of the charge-to-mass ratio of particles trapped by the Paul Trap for education
Paul traps are devices that confine particles using an oscillating electric
field and have been used in undergraduate experimental classes at universities.
Owing to the requirement of a high voltage of several thousand volts, no cases
of use in middle and high schools are available. Therefore, we developed an
all-in-one-type Paul trap device that included a high-voltage transformer. The
Paul trap can be equipped with three different types of electrode attachments,
ring-type, and linear-type , and the trap image can be observed using a
built-in web camera. For example, the charge-to-mass ratio of particles was
measured with different types of attachments, and it was shown that reasonable
values could be obtained. This type of trap is currently used at several
educational facilities in Japan.Comment: 6 pages, 12 figure
Spectroscopy of 24Al and extraction of Gamow-Teller strengths with the 24Mg(3He,t) reaction at 420 MeV
The 24Mg(3He,t)24Al reaction has been studied at E(3He)=420 MeV. An energy
resolution of 35 keV was achieved. Gamow-Teller strengths to discrete levels in
24Al are extracted by using a recently developed empirical relationship for the
proportionality between Gamow-Teller strengths and differential cross sections
at zero momentum transfer. Except for small discrepancies for a few weak
excitations, good agreement with previous 24Mg(p,n) data and nuclear-structure
calculations using the USDA/B interactions in the sd shell-model space is
found. The excitation energy of several levels in 24Al of significance for
determination of the 23Mg(p,gamma)24Al thermonuclear reaction rate were
measured. Results are consistent with two of the three previous (3He,t)
measurements, performed at much lower beam energies. However, a new state at
Ex(24Al)=2.605(10) MeV was found and is the third state above the proton
separation energy.Comment: 6 pages, 4 figure
Solving discrete logarithms on a 170-bit MNT curve by pairing reduction
Pairing based cryptography is in a dangerous position following the
breakthroughs on discrete logarithms computations in finite fields of small
characteristic. Remaining instances are built over finite fields of large
characteristic and their security relies on the fact that the embedding field
of the underlying curve is relatively large. How large is debatable. The aim of
our work is to sustain the claim that the combination of degree 3 embedding and
too small finite fields obviously does not provide enough security. As a
computational example, we solve the DLP on a 170-bit MNT curve, by exploiting
the pairing embedding to a 508-bit, degree-3 extension of the base field.Comment: to appear in the Lecture Notes in Computer Science (LNCS
Standard Model tests with trapped radioactive atoms
We review the use of laser cooling and trapping for Standard Model tests,
focusing on trapping of radioactive isotopes. Experiments with neutral atoms
trapped with modern laser cooling techniques are testing several basic
predictions of electroweak unification. For nuclear decay, demonstrated
trap techniques include neutrino momentum measurements from beta-recoil
coincidences, along with methods to produce highly polarized samples. These
techniques have set the best general constraints on non-Standard Model scalar
interactions in the first generation of particles. They also have the promise
to test whether parity symmetry is maximally violated, to search for tensor
interactions, and to search for new sources of time reversal violation. There
are also possibilites for exotic particle searches. Measurements of the
strength of the weak neutral current can be assisted by precision atomic
experiments using traps of small numbers of radioactive atoms, and sensitivity
to possible time-reversal violating electric dipole moments can be improved.Comment: 45 pages, 17 figures, v3 includes clarifying referee comments,
especially in beta decay section, and updated figure
Complete electric dipole response and the neutron skin in 208Pb
A benchmark experiment on 208Pb shows that polarized proton inelastic
scattering at very forward angles including 0{\deg} is a powerful tool for
high-resolution studies of electric dipole (E1) and spin magnetic dipole (M1)
modes in nuclei over a broad excitation energy range to test up-to-date nuclear
models. The extracted E1 polarizability leads to a neutron skin thickness
r_skin = 0.156+0.025-0.021 fm in 208Pb derived within a mean-field model [Phys.
Rev. C 81, 051303 (2010)], thereby constraining the symmetry energy and its
density dependence, relevant to the description of neutron stars.Comment: 5 pages, 5 figures, revised mansucrip
On the extraction of weak transition strengths via the (3He,t) reaction at 420 MeV
Differential cross sections for transitions of known weak strength were
measured with the (3He,t) reaction at 420 MeV on targets of 12C, 13C, 18O,
26Mg, 58Ni, 60Ni, 90Zr, 118Sn, 120Sn and 208Pb. Using this data, it is shown
the proportionalities between strengths and cross sections for this probe
follow simple trends as a function of mass number. These trends can be used to
confidently determine Gamow-Teller strength distributions in nuclei for which
the proportionality cannot be calibrated via beta-decay strengths. Although
theoretical calculations in distorted-wave Born approximation overestimate the
data, they allow one to understand the main experimental features and to
predict deviations from the simple trends observed in some of the transitions.Comment: 4 pages, 2 figure
The HERMES Dual-Radiator Ring Imaging Cerenkov Detector
The construction and use of a dual radiator Ring Imaging Cerenkov(RICH)
detector is described. This instrument was developed for the HERMES experiment
at DESY which emphasizes measurements of semi-inclusive deep-inelastic
scattering. It provides particle identification for pions, kaons, and protons
in the momentum range from 2 to 15 GeV, which is essential to these studies.
The instrument uses two radiators, C4F10, a heavy fluorocarbon gas, and a wall
of silica aerogel tiles. The use of aerogel in a RICH detector has only
recently become possible with the development of clear, large homogeneous and
hydrophobic aerogel. A lightweight mirror was constructed using a newly
perfected technique to make resin-coated carbon-fiber surfaces of optical
quality. The photon detector consists of 1934 photomultiplier tubes for each
detector half, held in a soft steel matrix to provide shielding against the
residual field of the main spectrometer magnet.Comment: 25 pages, 23 figure
Pygmy dipole resonance in 208Pb
Scattering of protons of several hundred MeV is a promising new spectroscopic
tool for the study of electric dipole strength in nuclei. A case study of 208Pb
shows that at very forward angles J^pi = 1- states are strongly populated via
Coulomb excitation. A separation from nuclear excitation of other modes is
achieved by a multipole decomposition analysis of the experimental cross
sections based on theoretical angular distributions calculated within the
quasiparticle-phonon model. The B(E1) transition strength distribution is
extracted for excitation energies up to 9 MeV, i.e., in the region of the
so-called pygmy dipole resonance (PDR). The Coulomb-nuclear interference shows
sensitivity to the underlying structure of the E1 transitions, which allows for
the first time an experimental extraction of the electromagnetic transition
strength and the energy centroid of the PDR.Comment: submitted to Phys. Rev.
Polarized light-flavor antiquarks from Drell-Yan processes of h+\vec{N}\to\vec{l^{+-}} + l^{-+} + X
We propose a formula to determine the first moment of difference between the
polarized - and -quarks in the nucleon, {\it i.e.} from the Drell-Yan processes in collisions of unpolarized
hadrons with longitudinally polarized nucleons by measuring outgoing lepton
helicities. As coefficients in the differential cross section depend on the
- and -quark numbers in the unpolarized hadron beam, the difference
can be independently tested by changing the hadron
beam. Moreover, a formula for estimating the -factor in Drell-Yan processes
is also suggested.Comment: 10 pages, 1 figur
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