An exceptionally bright new X-ray source in the Large Magellanic Cloud was discovered by the Swift/BAT telescope on MJD 54923 (2009 April 2), and shown to have a pulse period of 27 s using follow-up ...observations by RXTE/PCA (Krimm et al. 2009). We report here on detailed timing observations taken over the following weeks using Fermi/Gamma Ray Burst Monitor (GBM) which reveal an excellent orbital solution and indicate that the source flux is peaked at ∼1038 erg s−1. In addition, we report on follow-up optical observations (spectroscopic and photometric) which permit a classification of the mass donor star as B1Ve, and furthermore reveal a strong optical modulation at a period consistent with the binary period found from the Fermi/GBM data – 27.4 d. The dynamical mass estimate for the Be star is not in agreement with that expected for a B1V star – a mismatch similar to this has been previously reported for the few other Magellanic Cloud stars that also have dynamical mass estimates. In addition, the neutron star magnetic field determination from the X-ray data (∼1013 G) adds further evidence to the possibility that many such stars in high-mass X-ray binary systems may have magnetic fields greater than previously expected (∼1012 G).
Measuring the polarization of the prompt 7-ray emission from gamma-ray bursts (GRBs) can significantly improve our understanding of both the GRB emission mechanisms as well as the underlying engine ...driving the explosion. We searched for polarization in the prompt 7-ray emission of GRB 041219a with the SPI instrument on INTEGRAL. Using multiple-detector coincidence events in the 100-350 keV energy band, our analysis yields a polarization fraction from this GRB of 98% c 33%. Statistically, we cannot claim a polarization detection from this source. Moreover, different event selection criteria lead to even less significant polarization fractions, e.g., lower polarization fractions are obtained when higher energies are included in the analysis. We cannot strongly rule out the possibility that the measured modulation is dominated by instrumental systematics. Therefore, SPI observations of GRB 041219a do not significantly constrain GRB models. However, this measurement demonstrates the capability of SPI to measure polarization, as well as the techniques developed for this analysis.
Here we present the current state of the technical design of the SPHERE project’s new detector. The SPHERE project is aimed at primary cosmic ray studies in the 1–1000 PeV energy range using the ...reflected Cherenkov light method. The concept of a drone mounted detector with a photosensitive camera based on silicon photomultipliers is discussed. The design details of a small scale prototype of this detector is presented.
After about 18 yr of steadily spinning down, the accretion-powered pulsar 4U 1626-67 experienced a new torque reversal at the beginning of 2008. For the present study, we have used all available ...Fermi/Gamma-ray Burst Monitor data since its launch in 2008 June 11 and over 5 yr of hard X-ray Swift/Burst Alert Telescope observations (starting from 2004 October up to the present time). From 2004 up to the end of 2007 the spin-down rate averaged at a mean rate of Hz s-1 until the torque reversal reported here. This second detected torque reversal was centered near MJD 54500 (2008 February 4) and it lasted approximately 150 days. During the reversal, the source also underwent an increase in flux by a fraction of ~2.5. Since then it has been following a steady spin-up at a mean rate of Hz s-1. We present a detailed long-term timing analysis of this source and a long-term spectral hardness ratio study in order to see whether there are spectral changes around this new observed torque reversal.
In 2016 we have upgraded the COMPASS RICH by novel gaseous photon detectors based on MPGD technology. Four new photon detectors, covering a total active area of 1.5
m
2
, have been installed in order ...to cope with the challenging efficiency and stability requirements of the COMPASS physics programme. The new detector architecture consists in a hybrid MPGD combination: two layers of THGEMs, the first of which also acts as a reflective photocathode thanks to CsI coating, are coupled to a bulk Micromegas on a pad-segmented anode. These detectors are the first application in an experiment of MPGD-based single photon detectors. Presently, we are further developing the MPGD-based PDs to make them adequate for a setup at the future EIC collider. All aspects of the COMPASS RICH-1 Photon Detectors upgrade are presented: R&D, engineering, mass production, QA and performance; the on-going development for collider application is also presented.
THGEM based photon detector for Cherenkov imaging applications Alexeev, M.; Birsa, R.; Bradamante, F. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2010, Volume:
617, Issue:
1
Journal Article
Peer reviewed
We are developing a single photon detector for Cherenkov imaging counters. This detector is based on the use of THGEM electron multipliers in a multilayer design. The major goals of our project are ...ion feedback suppression down to a few per cent, large gain, fast response, insensitivity to magnetic fields, and a large detector size.
We report about the project status and perspectives. In particular, we present a systematic study of the THGEM response as a function of geometrical parameters, production techniques and the gas mixture composition. The first figures obtained from measuring the response of a CsI coated THGEM to single photons are presented.
Aims. In this Letter we present results from INTEGRAL and RXTE observations of the spectral and timing behavior of the High Mass X-ray Binary A 0535+26 during its August/September 2005 normal (type ...I) outburst with an average flux $F_{(5-100)}\,_{\mathrm{keV}} \sim400$ mCrab. The search for cyclotron resonance scattering features (fundamental and harmonic) is one major focus of the paper. Methods. Our analysis is based on data from INTEGRAL and RXTE Target of Opportunity Observations performed during the outburst. The pulse period is determined. X-ray pulse profiles in different energy ranges are analyzed. The broad band INTEGRAL and RXTE pulse phase averaged X-ray spectra are studied. The evolution of the fundamental cyclotron line at different luminosities is analyzed. Results.The pulse period P is measured to be 103.39315(5) s at MJD 53614.5137. Two absorption features are detected in the phase averaged spectra at $E_{1}\sim 45$ keV and $E_{2}\sim 100$ keV. These can be interpreted as the fundamental cyclotron resonance scattering feature and its first harmonic and therefore the magnetic field can be estimated to be $B\sim 4\times 10^{12}$ G.
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