295 research outputs found
Spin-independent elastic WIMP scattering and the DAMA annual modulation signal
We discuss the interpretation of the annual modulation signal seen in the
DAMA experiment in terms of spin-independent elastic WIMP scattering. Taking
into account channeling in the crystal as well as the spectral signature of the
modulation signal we find that the low-mass WIMP region consistent with DAMA
data is confined to WIMP masses close to GeV, in
disagreement with the constraints from CDMS and XENON. We conclude that even if
channeling is taken into account this interpretation of the DAMA modulation
signal is disfavoured. There are no overlap regions in the parameter space at
90% CL and a consistency test gives the probability of . We
study the robustness of this result with respect to variations of the WIMP
velocity distribution in our galaxy, by changing various parameters of the
distribution function, and by using the results of a realistic N-body dark
matter simulation. We find that only by making rather extreme assumptions
regarding halo properties can we obtain agreement between DAMA and CDMS/XENON.Comment: 21 pages, 12 figures, matches version accepted in JCA
Generalized Analysis of Weakly-Interacting Massive Particle Searches
We perform a generalized analysis of data from WIMP search experiments for
point-like WIMPs of arbitrary spin and general Lorenz-invariant WIMP-nucleus
interaction. We show that in the non-relativistic limit only spin-independent
(SI) and spin-dependent (SD) WIMP-nucleon interactions survive, which can be
parameterized by only five independent parameters. We explore this
five-dimensional parameter space to determine whether the annual modulation
observed in the DAMA experiment can be consistent with all other experiments.
The pure SI interaction is ruled out except for very small region of parameter
space with the WIMP mass close to 50 GeV and the ratio of the WIMP-neutron to
WIMP-proton SI couplings . For the predominantly SD
interaction, we find an upper limit to the WIMP mass of about 18 GeV, which can
only be weakened if the constraint stemming from null searches for energetic
neutrinos from WIMP annihilation the Sun is evaded. None of the regions of the
parameter space that can reconcile all WIMP search results can be easily
accommodated in the minimal supersymmetric extension of the standard model.Comment: 27 pages, 3 figure
Effect of halo modelling on WIMP exclusion limits
WIMP direct detection experiments are just reaching the sensitivity required
to detect galactic dark matter in the form of neutralinos. Data from these
experiments are usually analysed under the simplifying assumption that the
Milky Way halo is an isothermal sphere with maxwellian velocity distribution.
Observations and numerical simulations indicate that galaxy halos are in fact
triaxial and anisotropic. Furthermore, in the cold dark matter paradigm
galactic halos form via the merger of smaller subhalos, and at least some
residual substructure survives. We examine the effect of halo modelling on WIMP
exclusion limits, taking into account the detector response. Triaxial and
anisotropic halo models, with parameters motivated by observations and
numerical simulations, lead to significant changes which are different for
different experiments, while if the local WIMP distribution is dominated by
small scale clumps then the exclusion limits are changed dramatically.Comment: 9 pages, 9 figures, version to appear in Phys. Rev. D, minor change
Possible implications of the channeling effect in NaI(Tl) crystals
The channeling effect of low energy ions along the crystallographic axes and
planes of NaI(Tl) crystals is discussed in the framework of corollary
investigations on WIMP Dark Matter candidates. In fact, the modeling of this
existing effect implies a more complex evaluation of the luminosity yield for
low energy recoiling Na and I ions. In the present paper related
phenomenological arguments are developed and possible implications are
discussed at some extent.Comment: 16 pages, 10 figures, preprint ROM2F/2007/15, submitted for
publicatio
Predicted modulated differential rates for direct WIMP searches at low energy transfers
The differential event rate for direct detection of dark matter, both the
time averaged and the modulated one due to the motion of the Earth, are
discussed. The calculations focus on relatively light cold dark matter
candidates (WIMP) and low energy transfers. It is shown that for sufficiently
light WIMPs the extraction of relatively large nucleon cross sections is
possible. Furthermore for some WIMP masses the modulation amplitude may change
sign, meaning that, in such a case, the maximum rate may occur six months later
than naively expected. This effect can be exploited to yield information about
the mass of the dark matter candidate, if and when the observation of the
modulation of the event rate is established.Comment: 16 pages, 22 figures; references adde
PATIENT VOICES, a project for the integration of the systematic assessment of patient reported outcomes and experiences within a comprehensive cancer center: a protocol for a mixed method feasibility study
BACKGROUND: Listening to "patient voices" in terms of symptoms, emotional status and experiences with care, is crucial for patient empowerment in clinical practice. Despite convincing evidence that routine patient reported outcomes and experience measurements (PRMs) with rapid feed-back to oncologists can improve symptom control, patient well-being and cost effectiveness, PRMs are not commonly used in cancer care, due to barriers at various level. Part of these barriers may be overcome through electronic PRMs collection (ePRMs) integrated with the electronic medical record (EMR). The PATIENT VOICES initiative is aimed at achieving a stepwise integration of ePRMs assessment into routine cancer care. The feasibility project presented here is aimed at assessing the knowledge, use and attitudes toward PRMs in a comprehensive cancer centre; developing and assessing feasibility of a flexible system for ePRM assessment; identifying barriers to and developing strategies for implementation and integration of ePRMs clinical practice. METHODS: The project has been organized into four phases: a) pre-development; b) software development and piloting; c) feasibility assessment; d) post-development. A convergent mixed method design, based on concurrent quantitative and qualitative data collection will be applied. A web-survey on health care providers (HCPs), qualitative studies on patients and HCPs (semi-structured interviews and focus groups) as well as longitudinal and cross-sectional quantitative studies will be carried out. The quantitative studies will enroll 600 patients: 200 attending out-patient clinics (physical symptom assessement), 200 attending inpatient wards (psychological distress assessment) and 200 patients followed by multidisciplinary teams (patient experience with care assessment). The Edmonton symptom assessment scale, the Distress Thermometer, and a tool adapted from existing patient reported experience with cancer care questionnaires, will be used in quantitative studies. A multi-disciplinary stakeholder team including researchers, clinicians, health informatics professionals, health system administrators and patients will be involved in the development of potentially effective implementation strategies in the post development phase. DISCUSSION: The documentation of potential advantages and implementation barriers achieved within this feasibility project, will serve as a starting point for future and more focused interventions aimed at achieving effective ePRMs routine assessment in cancer care. TRIAL REGISTRATION: ClinicalTrials.gov ( NCT03968718 ) May 30th, 2019
New data on OZI rule violation in bar{p}p annihilation at rest
The results of a measurement of the ratio R = Y(phi pi+ pi-) / Y(omega pi+
pi-) for antiproton annihilation at rest in a gaseous and in a liquid hydrogen
target are presented. It was found that the value of this ratio increases with
the decreasing of the dipion mass, which demonstrates the difference in the phi
and omega production mechanisms. An indication on the momentum transfer
dependence of the apparent OZI rule violation for phi production from the 3S1
initial state was found.Comment: 11 pages, 3 PostScript figures, submitted to Physics Letter
An actively vetoed Clover gamma-detector for nuclear astrophysics at LUNA
An escape-suppressed, composite high-purity germanium detector of the Clover
type has been installed at the Laboratory for Underground Nuclear Astrophysics
(LUNA) facility, deep underground in the Gran Sasso Laboratory, Italy. The
laboratory gamma-ray background of the Clover detector has been studied
underground at LUNA and, for comparison, also in an overground laboratory.
Spectra have been recorded both for the single segments and for the virtual
detector formed by online addition of all four segments. The effect of the
escape-suppression shield has been studied as well. Despite their generally
higher intrinsic background, escape-suppressed detectors are found to be well
suited for underground nuclear astrophysics studies. As an example for the
advantage of using a composite detector deep underground, the weak ground state
branching of the Ep = 223 keV resonance in the 24Mg(p,gamma)25Al reaction is
determined with improved precision.Comment: 8 pages, 6 figures, 3 tables; as accepted by Eur. Phys. J.
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