Compact binary coalescences, such as binary neutron stars or black holes, are among the most promising candidate sources for the current and future terrestrial gravitational-wave detectors. While ...such sources are best searched using matched template techniques and chirp template banks, integrating chirp signals from binaries over the entire universe also leads to a gravitational-wave background (GWB). In this paper we systematically scan the parameter space for the binary coalescence GWB models, taking into account uncertainties in the star formation rate and in the delay time between the formation and coalescence of the binary, and we compare the computed GWB to the expected sensitivities of the second and third generation gravitational-wave detector networks. We find that second generation detectors are likely to detect the binary coalescence GWB, while the third generation detectors will probe most of the available parameter space. The binary coalescence GWB will, in fact, be a foreground for the third generation detectors, potentially masking the GWB background due to cosmological sources. Accessing the cosmological GWB with third generation detectors will therefore require identification and subtraction of all inspirai signals from all binaries in the detectors' frequency band.
Stellar core collapse events are expected to produce gravitational waves via several mechanisms, most of which are not yet fully understood due to the current limitations in the numerical simulations ...of these events. In this paper, we begin with an empirical functional form that fits the gravitational-wave spectra from existing simulations of stellar core collapse and integrate over all collapse events in the Universe to estimate the resulting stochastic gravitational-wave background. We then use a Gaussian functional form to separately fit and model a low-frequency peak in the core-collapse strain spectra, which likely occurs due to prompt convection. We systematically study the parameter space of both models, as well as the combined case, and investigate their detectability by upcoming gravitational-wave detectors, such as Advanced LIGO and the Einstein Telescope. Assuming realistic formation rates for progenitors of core-collapse supernovae, our results indicate that both models are 2–4 orders of magnitude below the expected sensitivity of Advanced LIGO, and 1–2 orders of magnitude below that of the Einstein Telescope.
The stochastic gravitational-wave background (SGWB) is expected to arise from the superposition of many independent and unresolved gravitational-wave signals of either cosmological or astrophysical ...origin. The spectral content of the SGWB carries signatures of the physics that generated it. We present a Bayesian framework for estimating the parameters associated with different SGWB models using data from gravitational-wave detectors. We apply this technique to recent results from LIGO to produce the first simultaneous 95% confidence level limits on multiple parameters in generic power-law SGWB models and in SGWB models of compact binary coalescences. We also estimate the sensitivity of the upcoming second-generation detectors such as Advanced LIGO or Virgo to these models and demonstrate how SGWB measurements can be combined and compared with observations of individual compact binary coalescences in order to build confidence in the origin of an observed SGWB signal. In doing so, we demonstrate a novel means of differentiating between different sources of the SGWB.
A stochastic gravitational-wave background (SGWB) is expected to arise from the superposition of many independent and unresolved gravitational-wave signals, of either cosmological or astrophysical ...origin. Some cosmological models (characterized, for instance, by a pseudo-scalar inflaton, or by some modification of gravity) break parity, leading to a polarized isotropic SGWB. We present the first upper limit on this parity violation from direct gravitational-wave measurements by measuring polarization of the SGWB in recent LIGO data and by assuming a generic power-law SGWB spectrum across the LIGO-sensitive frequency region. We also estimate sensitivity to parity violation for future generations of gravitational-wave detectors, both for a power-law spectrum and for a specific model of axion inflation. Since astrophysical sources are not expected to produce a polarized SGWB, measurements of polarization in the SGWB would provide a new way of differentiating between the cosmological and astrophysical SGWB sources.
We review the spectral properties of stochastic backgrounds of astrophysical origin and discuss how they may differ from the primordial contribution by their statistical properties. We show that ...stochastic searches with the next generation of terrestrial interferometers could put interesting constraints on the physical properties of astrophysical populations, such as the ellipticity and magnetic field of magnetars, or the coalescence rate of compact binaries.
For the first time, time-dependent internal charge amplification through impact ionization has been observed in a planar germanium (Ge) detector operated at cryogenic temperature. In a time period of ...30 and 45 min after applying a bias voltage, the charge energy corresponding to a baseline of the 59.54 keV
γ
rays from a
241
Am source is amplified for a short period of time and then decreases back to the baseline. The amplification of charge energy depends strongly on the applied positive bias voltage with drifting holes across the detector. No such phenomenon is visible with drifting electrons across the detector. We find that the observed charge amplification is dictated by the impact ionization of charged states, which has a strong correlation with impurity level and applied electric field. We analyze the dominant physics mechanisms that are responsible for the creation and the impact ionization of charged states. Our analysis suggests that the appropriate level of impurity in a Ge detector can enhance charge yield through the impact ionization of charged states to achieve extremely low-energy detection threshold (< 10 meV) for MeV-scale dark matter searches if the charge amplification can be stabilized.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The proposed Mitchell Institute Neutrino Experiment at Reactor (MINER) experiment at the Nuclear Science Center at Texas A&M University will search for coherent elastic neutrino-nucleus scattering ...within close proximity (about 2m) of a 1MW TRIGA nuclear reactor core using low threshold, cryogenic germanium and silicon detectors. Given the Standard Model cross section of the scattering process and the proposed experimental proximity to the reactor, as many as 5–20events/kg/day are expected. We discuss the status of preliminary measurements to characterize the main backgrounds for the proposed experiment. Both in situ measurements at the experimental site and simulations using the MCNP and GEANT4 codes are described. A strategy for monitoring backgrounds during data taking is briefly discussed.
IntroductionParent-mediated interventions for children with autism spectrum disorder (ASD) have beend recognized as very valuable (1). There is a significant effect of parental attitudes towards ...treatment on treatment outcomes (2).ObjectivesTo evaluate parental attitudes and need for professional support regarding pharmacological treatment of children with ASD.MethodsWe interviewed 67 parents (83.6% mothers) of children with ASD who are regularly treated at our institution. We created a questionnaire with sociodemografic information, clinical characteristics of the child, and parental experience/attitudes on pharmacological treatment.ResultsThe average child age was 20.06±4.43; 80.6% were male. The child clinical characteristics and parental sociodemographics are shown Table 1.Table 1.Clinical characteristics of children with ASD/parental sociodemographicsClinical characteristics – childrenNValid %XSDSpeech - 4 words or more3552.2Epilepsy1319.4Intellectual dissability2131.3Parental sociodemographicsCurrent age of parent (informant)50.936.91Parent (informant) educationPrimary and secondary schoolAttended/finished university or postgraduate degree254237.362.7Parent (non-informant) educationPrimary and secondary schoolAttended/finished university or postgraduate degree31354753Parental attitudes and feelings when child is treated with medication are shown in Graph 1.Graph 1. Parental attitudes on medicationWe also examined what would help parents in reaching the decision on pharmacotherapy for their children (the results shown in Graph 2).Graph 2. Parental need of support for decision on medicationIn our further analysis, it was shown that the feeling of guilt and helplesness was significantly more present in parents who feared side-effects of medication (p=0.016 and p˂0.001, respectively).Image:Image 2:ConclusionsA significant number of parents battle with feelings of helplesness and guilt when medication is introduced in the treatment of their children. There is a great need for information provided by the clinicians as well as psychological support in reaching shared decisions regarding pharmacological treatment of children with ASD.References:1. Wang F, Lao UC, Xing YP, Zhou P, Deng WL, Wang Y, et al. Parents’ knowledge and attitude and behavior toward autism: a survey of Chinese families having children with autism spectrum disorder. Transl Pediatr. 2022 Sep;11(9):1445-1457.2. Hock R, Kinsman A, Ortaglia A. Examining treatment adherence among parents of children with autism spectrum disorder. Disabil Health J. 2015 Jul;8(3):407-13.Disclosure of InterestNone Declared
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