Unrevealed aspects of the photoinduced phase transition are discussed with a special emphasis placed on domains and domain boundaries. The CN− vibration spectroscopy, which is sensitive to the phase ...changes and boundaries, is applied to photomagnetic phase transition material, RbMnFe(CN)6. From time‐resolved IR measurements for photoinduced low temperature to high temperature phase transition, the transient appearance of the boundaries as well as the new phase within 1 ps is observed. The growth processes of the low temperature phase and boundaries during UV irradiation on the sample in high temperature phase are investigated by Raman spectroscopy at room temperature. The result suggests that the new phase appears preferably in the fresh area and a lot of unpaired fragments of high temperature phase are left behind after a prolonged irradiation.
Typical distribution of two phases and boundaries in hexacyanoferrate during photoinduced phase transition (simulation). Blue: initial phase; red: new phase; green: boundary.
Protons with energies up to ∼1015 eV are the main component of cosmic rays, but evidence for the specific locations where they could have been accelerated to these energies has been lacking. ...Electrons are known to be accelerated to cosmic-ray energies in supernova remnants, and the shock waves associated with such remnants, when they hit the surrounding interstellar medium, could also provide the energy to accelerate protons. The signature of such a process would be the decay of pions (π0), which are generated when the protons collide with atoms and molecules in an interstellar cloud: pion decay results in γ-rays with a particular spectral-energy distribution. Here we report the observation of cascade showers of optical photons resulting from γ-rays at energies of ∼1012 eV hitting Earth's upper atmosphere, in the direction of the supernova remnant RX J1713.7-3946. The spectrum is a good match to that predicted by pion decay, and cannot be explained by other mechanisms.
Sub-TeV gamma-ray emission from the northwest rim of the supernova remnant RX J0852.0-4622 was detected with the CANGAROO II telescope and recently confirmed by the HESS group. In addition, the HESS ...data revealed a very wide (up to 2 in diameter), shell-like profile of the gamma-ray emission. We carried out CANGAROO III observations in 2005 January and February with three telescopes and show here the results of threefold coincidence data. We confirm the HESS results about the morphology and the energy spectrum and find that the energy spectrum in the NW rim is consistent with that of the whole remnant.
We made stereoscopic observations of the Vela pulsar region with two of the 10 m diameter CANGAROO-III imaging atmospheric Cerenkov telescopes in 2004 January and February in a search for sub-TeV ...gamma rays from the pulsar and surrounding regions. We describe the observations, provide a detailed account of the calibration methods, and introduce the improved and bias-free analysis techniques employed for CANGAROO-III data. No evidence of gamma-ray emission is found from either the pulsar position or the previously reported position offset by 0 13, and the resulting upper limits are a factor of 5 less than the previously reported flux from observations with the CANGAROO-I 3.8 m telescope. Following the recent report by the H.E.S.S. group of TeV gamma-ray emission from the pulsar wind nebula, which is 60 5 south of the pulsar position, we examined this region and found supporting evidence for emission extended over 60 6.
SS433, located at the center of the supernova remnant W50, is a close proximity binary system consisting of a compact star and a normal star. Jets of material are directed outwards from the vicinity ...of the compact star symmetrically to the east and west. Non-thermal hard X-ray emission is detected from lobes lying on both sides. Shock accelerated electrons are expected to generate VHE gamma rays through the inverse-Compton process in the lobes. Observations of the western X-ray lobe region of SS433/W50 system have been performed to detect VHE gamma rays using the 10
m CANGAROO-II telescope in August and September, 2001, and July and September, 2002. The total observation times are 85.2
h for ON source, and 80.8
h for OFF source data. No significant excess of VHE gamma rays has been found at three regions of the western X-ray lobe of SS433/W50 system. We have derived 99% confidence level upper limits to the fluxes of gamma rays and have set constraints on the strengths of the magnetic fields assuming the synchrotron/inverse-Compton model for the wide energy range of photon spectrum from radio to TeV. The derived lower limits are
4.3
μ
G for the center of the brightest X-ray emission region and
6.3
μ
G for the far end from SS433 in the western X-ray lobe. In addition, we suggest that the spot-like X-ray emission may provide a major contribution to the hardest X-ray spectrum in the lobe.
Observations of the PSR B1259-63/SS 2883 binary system using the CANGAROO-II Cerenkov telescope are reported. This nearby binary consists of a 48 ms radio pulsar in a highly eccentric orbit around a ...Be star and offers a unique laboratory to investigate the interactions between the outflows of the pulsar and Be star at various distances. It has been pointed out that the relativistic pulsar wind and the dense mass outflow of the Be star may result in the emission of gamma rays up to TeV energies. We have observed the binary in 2000 and 2001, approx47 and approx157 days after the 2000 October periastron. Upper limits at the 0.13-0.54 crab level are obtained. A new model calculation for high- energy gamma-ray emission from the Be star outflow is introduced, and the estimated gamma-ray flux, considering bremsstrahlung, inverse Compton scattering, and the decay of neutral pions produced in proton-proton interactions, is found to be comparable to the upper limits of these observations. Comparing our results with these model calculations, we constrain the mass-outflow parameters of the Be star.
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