| 1. |
- Abdo, A. A., et al.
(författare)
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Fermi large area telescope observations of PSR J1836+5925
- 2010
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 712:2, s. 1209-1218
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Tidskriftsartikel (refereegranskat)abstract
- The discovery of the gamma-ray pulsar PSR J1836+5925, powering the formerly unidentified EGRET source 3EG J1835+5918, was one of the early accomplishments of the Fermi Large Area Telescope (LAT). Sitting 25 degrees off the Galactic plane, PSR J1836+5925 is a 173 ms pulsar with a characteristic age of 1.8 million years, a spindown luminosity of 1.1 x 10(34) erg s(-1), and a large off-peak (OP) emission component, making it quite unusual among the known gamma-ray pulsar population. We present an analysis of one year of LAT data, including an updated timing solution, detailed spectral results, and a long-term light curve showing no indication of variability. No evidence for a surrounding pulsar wind nebula is seen and the spectral characteristics of the OP emission indicate it is likely magnetospheric. Analysis of recent XMM-Newton observations of the X-ray counterpart yields a detailed characterization of its spectrum, which, like Geminga, is consistent with that of a neutron star showing evidence for both magnetospheric and thermal emission.
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| 2. |
- Abdo, A. A., et al.
(författare)
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DETECTION OF THE ENERGETIC PULSAR PSR B1509-58 AND ITS PULSAR WIND NEBULA IN MSH 15-52 USING THE FERMI-LARGE AREA TELESCOPE
- 2010
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 714:1, s. 927-936
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Tidskriftsartikel (refereegranskat)abstract
- We report the detection of high-energy gamma-ray emission from the young and energetic pulsar PSR B1509-58 and its pulsar wind nebula (PWN) in the composite supernova remnant G320.4-1.2 (aka MSH 15-52). Using 1 yr of survey data with the Fermi-Large Area Telescope (LAT), we detected pulsations from PSR B1509-58 up to 1 GeV and extended gamma-ray emission above 1 GeV spatially coincident with the PWN. The pulsar light curve presents two peaks offset from the radio peak by phases 0.96 +/- 0.01 and 0.33 +/- 0.02. New constraining upper limits on the pulsar emission are derived below 1 GeV and confirm a severe spectral break at a few tens of MeV. The nebular spectrum in the 1-100 GeV energy range is well described by a power law with a spectral index of (1.57 +/- 0.17 +/- 0.13) and a flux above 1 GeV of (2.91 +/- 0.79 +/- 1.35) x 10(-9) cm(-2) s(-1). The first errors represent the statistical errors on the fit parameters, while the second ones are the systematic uncertainties. The LAT spectrum of the nebula connects nicely with Cherenkov observations, and indicates a spectral break between GeV and TeV energies.
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| 3. |
- Takahashi, H., et al.
(författare)
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The Polarized Gamma-Ray Observer, PoGOLite
- 2010
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Ingår i: Transactions of the Japanese Society for Artificial Intelligence, Aerospace Technology Japan. - 1346-0714 .- 1346-0714. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- The Polarized Gamma-ray Observer, PoGOLite, is a balloon experiment with the capability of detecting 10% polarization from a 200 mCrab celestial object in the energy-range 25–80 keV. During a beam test at KEK-PF in 2008, 19 detector units and one anti-coincidence detector were assembled, and a 50 keV X-ray beam with a polarization degree of ∼90% was irradiated at the center unit. Signals from all 20 units were fed into flight-version electronics consisting of six circuit boards (four waveform digitizer boards, one digital I/O board and one router board) and one microprocessor (SpaceCube), which communicate using a SpaceWire interface. One digitizer board, which can associate up to 8 detectors, outputs a trigger signal. The digital I/O board handles the trigger and returns a data acquisition request if there is no veto signal (upper or pulse-shape discriminators) from any detector unit. This data acquisition system worked well, and the modulation factor was successfully measured to be ∼34%. These results confirmed the capabilities of the data-acquisition system for a “pathfinder” flight planned in 2010.
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| 4. |
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| 5. |
- Takahashi, H., et al.
(författare)
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A thermal-neutron detector with a phoswich system of LiCaAlF6 and BGO crystal scintillators onboard PoGOLite
- 2010
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Ingår i: 2010 IEEE Nuclear Science Symposium, Medical Imaging Conference, NSS/MIC 2010 and 17th International Workshop on Room-Temperature Semiconductor X-ray and Gamma-ray Detectors, RTSD 2010. ; , s. 32-37
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Konferensbidrag (refereegranskat)abstract
- To measure the flux of atmospheric neutrons and study the neutron contribution to the background of the main detector of the PoGOLite (Polarized Gamma-ray Observer) balloon-borne experiment, a thermal-neutron detector with a phoswich system of LiCaAlF6 (Eu) and BGO crystal scintillators is developed. The performance to separate thermal-neutron events from those of gamma-rays and charged particles is validated with 252Cf on ground. The detector is attached to the PoGOLite instrument and is launched in 2011 from the Esrange facility in the North of Sweden. Although the emission wavelength of the LiCaAlF6 (Ce) is 300 nm and overlaps with the absorption wavelength of the BGO, the phoswich capability of the LiCaAlF6 (Ce) with the BGO is also confirmed with installing a waveform shifter.
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| 6. |
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| 7. |
- Harpham, Michael R., et al.
(författare)
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X-ray Transient Absorption and Picosecond IR Spectroscopy of Fulvalene(tetracarbonyl)diruthenium on Photoexcitation
- 2012
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Ingår i: Angewandte Chemie - International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 51:31, s. 7692-7696
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Tidskriftsartikel (refereegranskat)abstract
- Caught in the light: The fulvalene diruthenium complex shown on the left side of the picture captures sun light, causing initial Ru–Ru bond rupture to furnish a long-lived triplet biradical of syn configuration. This species requires thermal activation to reach a crossing point (middle) into the singlet manifold on route to its thermal storage isomer on the right through the anti biradical.
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