395 research outputs found
Buffer-gas cooling of ion beams
The cooling action of a buffer gas on ions contained within it can be used to cool an ion beam, thereby greatly improving its emittance and energy spread. It can also be used to greatly enhance the collection of an ion beam in an electromagnetic trap. The basic principles will be introduced in the context of the development of a system for cooling ISOLDE beams for the ISOLTRAP facility
Dark energy, antimatter gravity and geometry of the Universe
This article is based on two hypotheses. The first one is the existence of
the gravitational repulsion between particles and antiparticles. Consequently,
virtual particle-antiparticle pairs in the quantum vacuum may be considered as
gravitational dipoles. The second hypothesis is that the Universe has geometry
of a four-dimensional hyper-spherical shell with thickness equal to the Compton
wavelength of a pion, which is a simple generalization of the usual geometry of
a 3-hypersphere. It is striking that these two hypotheses lead to a simple
relation for the gravitational mass density of the vacuum, which is in very
good agreement with the observed dark energy density
Production and trapping of carbon clusters for absolute mass measurements at ISOLTRAP
Singly-charged carbon clusters C/sub n//sup +/ (n >or= 1) have been produced by laser-induced desorption and fragmentation of C/sub 60/ fullerenes and have been injected into and stored in the Penning trap system of the ISOLTRAP mass spectrometer at ISOLDE/CERN. The present study is the first step to extend the until now direct mass measurements at ISOLTRAP to absolute mass measurements by using clusters of /sup 12/C. (10 refs)
Q-value of the superallowed beta decay of Ga-62
Masses of the radioactive isotopes 62Ga, 62Zn and 62Cu have been measured at
the JYFLTRAP facility with a relative precision of better than 18 ppb. A Q_EC
value of (9181.07 +- 0.54) keV for the superallowed decay of 62Ga is obtained
from the measured cyclotron frequency ratios of 62Ga-62Zn, 62Ga-62Ni and
62Zn-62Ni ions. The resulting Ft-value supports the validity of the conserved
vector current hypothesis (CVC). The mass excess values measured were (-51986.5
+-1.0) keV for 62Ga, (-61167.9 +- 0.9) keV for 62Zn and (-62787.2 +- 0.9) keV
for 62Cu.Comment: 12 pages, 3 figures, 2 tables, submitted to Phys. Lett. B. v2: added
acknowledgement
What would be outcome of a Big Crunch?
I suggest the existence of a still undiscovered interaction: repulsion
between matter and antimatter. The simplest and the most elegant candidate for
such a force is gravitational repulsion between particles and antiparticles. I
argue that such a force may give birth to a new Universe; by transforming an
eventual Big Crunch of our universe, to an event similar to Big Bang. In fact,
when a collapsing Universe is reduced to a supermassive black hole of a small
size, a very strong field of the conjectured force may create
particle-antiparticle pairs from the surrounding vacuum. The amount of the
antimatter created from the physical vacuum is equal to the decrease of mass of
"black hole Universe" and violently repelled from it. When the size of the
black hole is sufficiently small the creation of antimatter may become so huge
and fast, that matter of our Universe may disappear in a fraction of the Planck
time. So fast transformation of matter to antimatter may look like a Big Bang
with the initial size about 30 orders of magnitude greater than the Planck
length, questioning the need for inflation. In addition, a Big Crunch, of a
Universe dominated by matter, leads to a new Universe dominated by antimatter,
and vice versa; without need to invoke CP violation as explanation of
matter-antimatter asymmetry. Simply, our present day Universe is dominated by
matter, because the previous Universe was dominated by antimatter
Position-sensitive ion detection in precision Penning trap mass spectrometry
A commercial, position-sensitive ion detector was used for the first time for
the time-of-flight ion-cyclotron resonance detection technique in Penning trap
mass spectrometry. In this work, the characteristics of the detector and its
implementation in a Penning trap mass spectrometer will be presented. In
addition, simulations and experimental studies concerning the observation of
ions ejected from a Penning trap are described. This will allow for a precise
monitoring of the state of ion motion in the trap.Comment: 20 pages, 13 figure
From direct to absolute mass measurements: a study of the accuracy of ISOLTRAP
For a detailed study of the accuracy of the Penning trap mass spectrometer ISOLTRAP all expected sources of uncertainty were investigated with respect to their contributions to the uncertainty of the final result. In the course of these investigations, cross-reference measurements with singly charged carbon clusters C were carried out. The carbon cluster ions were produced by use of laser-induced desorption, fragmentation, and ionization of C fullerenes and injected into and stored in the Penning trap system. The comparison of the cyclotron frequencies of different carbon clusters has provided detailed insight into the residual systematic uncertainty of \acro{ISOLTRAP} and yielded a value of . This also represents the current limit of mass accuracy of the apparatus. Since the unified atomic mass unit is defined as 1/12 of the mass of the C atom, it will be possible to carry out absolute mass measurements with \acro{ISOLTRAP} in the future.\\[1\baselineskip] PACS: 07.75.+h (Mass spectrometers and related techniques), 21.10.Dr (Binding energies and masses), 32.10.Bi (Atomic masses, mass spectra, abundances, and isotopes), 36.40.Wa (Charged clusters)
Penning trap mass measurements on (99-109)$Cd with ISOLTRAP and implications on the rp process
Penning trap mass measurements on neutron-deficient Cd isotopes (99-109)Cd
have been performed with the ISOLTRAP mass spectrometer at ISOLDE/CERN, all
with relative mass uncertainties below 3*10^8. A new mass evaluation has been
performed. The mass of 99Cd has been determined for the first time which
extends the region of accurately known mass values towards the doubly magic
nucleus 100Sn. The implication of the results on the reaction path of the rp
process in stellar X-ray bursts is discussed. In particular, the uncertainty of
the abundance and the overproduction created by the rp-process for the mass A =
99 is demonstrated by reducing the uncertainty of the proton-separation energy
of 100In Sp(100In) by a factor of 2.5.Comment: 14 pages, 9 figure
Evidence for a breakdown of the Isobaric Multiplet Mass Equation: A study of the A=35, T=3/2 isospin quartet
Mass measurements on radionuclides along the potassium isotope chain have
been performed with the ISOLTRAP Penning trap mass spectrometer. For 35K
T1/2=178ms) to 46K (T1/2=105s) relative mass uncertainties of 2x10-8 and better
have been achieved. The accurate mass determination of 35K (dm=0.54keV) has
been exploited to test the Isobaric Multiplet Mass Equation (IMME) for the
A=35, T=3/2 isospinquartet. The experimental results indicate a deviation from
the generally adopted quadratic form.Comment: 8 pages, 4 figure
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