45 research outputs found
Reduction of EUVE Guest Observer Data
We report on the observation of the HI filament LVC 88+36-2 with the Deep Survey/Spectrometers of EUVE. Detecting the shadow of this cloud in absorption might have proven the existence of a diffuse EUV background behind the cloud, and constrain the emission geometries of the hot plasma in the Local Interstellar Medium (LISM). By detecting diffuse emission in the EUVE spectrometers, it would also be possible to constrain the temperature and pressure of the emitting regions as well as determine whether or not the hot phase of the LISM is in equilibrium with cosmic elemental abundances. Unfortunately, we did not detect a cloud shadow with this set of observations. This is due to a combination of circumstances, but mostly due to the fact that EUV diffuse emission is weak compared to the background levels of EUVE. If a shadow exists in the EUVE, then it is less than 1% of the EUVE detector background of 1e-3 cts arcmin(exp -2) in the Deep Survey detector
The Diffuse Extreme Ultraviolet Background
Observations of the diffuse EUV background towards 138 different directions using the spectrometers aboard the Extreme Ultraviolet Explorer satellite (EUVE) have been combined into a spectrum from 150A to 730A and represent an effective exposure of 18 million seconds. There is no significant evidence of any non-local line flux in the resultant spectrum such as that from a hot coronal plasma. These results are inconsistent with the Wisconsin C and B broad-band surveys assuming the source is a logT = 5.8 - 6.1 hot plasma in ionization equilibrium with solar abundances, confirming the previous result of Jelinksy, Vallerga and Edelstein) (hereafter Paper 1) using an observation along the ecliptic with the same instrument. To make these results consistent with the previous broad-band surveys, the plasma responsible for the emission must either be depleted in Fe by a factor of approximately 6, be behind an absorbing slab of neutral H with a column of 2 x 10(exp 19)/sq cm, or not be in collisional ionization equilibrium (CIE). One such non-CIE model (Breitswerdt and Schmutzier) that explains the soft x-ray results is also inconsistent with this EUV data
A Search for EUV Emission from the O4f Star Zeta Puppis
We obtained a 140 ks EUVE observation of the O4f star, zeta Puppis. Because of its low ISM column density and highly ionized stellar wind, a unique EUV window is accessible for viewing between 128 to 140 A, suggesting that this star may he the only O star observable with the EUVE. Although no SW spectrometer wavelength bin had a signal to noise greater than 3, a bin at 136 A had a signal to noise of 2.4. This bin is where models predict the brightest line due to OV emission should occur. We present several EUV line emission models. These models were constrained by fitting the ROSAT PSPC X-ray data and our EUVE data. If the OV emission is real, the best fits to the data suggest that there are discrepancies in our current understanding of EUV/X-ray production mechanisms. In particular, the emission measure of the EUV source is found to be much greater than the total wind emission measure, suggesting that the EUV shock must produce a very large density enhancement. In addition, the location of the EUV and X-ray shocks are found to be separated by approx. 0.3 stellar radii, but the EUV emission region is found to be approx. 400 times larger than the X-ray emission region. We also discuss the implications of a null detection and present relevant upper limits
Three dimensional photograph of single electron tracks through a scintillator
The reconstruction of particle trajectories makes it possible to distinguish
between different types of charged particles. In high-energy physics, where
trajectories are rather long, large size trackers must be used to achieve
sufficient position resolution. However, in low-background experiments tracks
are rather short and three dimensional trajectories could only be resolved in
time-projection chambers so far. For detectors of large volume and therefore
large drift distances, which are inevitable for low-background experiments,
this technique is limited by diffusion of charge carriers. In this work we
present a "proof-of-principle" experiment for a new method for the three
dimensional tracking of charged particles by scintillation light: We used a
setup consisting of a scintillator, mirrors, lenses and a novel imaging device
(the hybrid photo detector) in order to image two projections of electron
tracks through the scintillator. We took data at the T-24 beam-line at DESY
with relativistic electrons with a kinetic energy of 5 GeV and from this data
successfully reconstructed their three dimensional propagetion path in the
scintillator. With our setup we achieved a position resolution of about 28 mum
in the best case.Comment: 9 pages, 13 figures, 1 tabl
Detection of non-classical space-time correlations with a novel type of single-photon camera
During the last decades, multi-pixel detectors have been developed capable of
registering single photons. The newly developed Hybrid Photon Detector camera
has a remarkable property that it has not only spatial but also temporal
resolution. In this work, we use this device for the detection of non-classical
light from spontaneous parametric down-conversion and use two-photon
correlations for the absolute calibration of its quantum efficiency
Cosmic Origins (COR) Program Technology Development 2018
No abstract availabl
Possible detection of two giant extrasolar planets orbiting the eclipsing polar UZ Fornacis
We present new high-speed, multi-observatory, multi-instrument photometry of
the eclipsing polar UZ For in order to measure precise mid-eclipse times with
the aim of detecting any orbital period variations. When combined with
published eclipse times and archival data spanning ~27 years, we detect
departures from a linear and quadratic trend of ~60 s. The departures are
strongly suggestive of two cyclic variations of 16(3) and 5.25(25) years. The
two favoured mechanisms to drive the periodicities are either two giant
extrasolar planets as companions to the binary (with minimum masses of
6.3(1.5)M(Jupiter) and 7.7(1.2)M(Jupiter)) or a magnetic cycle mechanism (e.g.
Applegate's mechanism) of the secondary star. Applegate's mechanism would
require the entire radiant energy output of the secondary and would therefore
seem to be the least likely of the two, barring any further refinements in the
effect of magnetic fieilds (e.g. those of Lanza et al.). The two planet model
can provide realistic solutions but it does not quite capture all of the
eclipse times measurements. A highly eccentric orbit for the outer planet would
fit the data nicely, but we find that such a solution would be unstable. It is
also possible that the periodicities are driven by some combination of both
mechanisms. Further observations of this system are encouraged.Comment: 10 pages, 4 figures, 2 table
Ion-ion coincidence imaging at high event rate using an in-vacuum pixel detector
A new ion-ion coincidence imaging spectrometer based on a pixelated
complementary metal-oxide-semiconductor detector has been developed for the
investigation of molecular ionization and fragmentation processes in strong
laser fields. Used as a part of a velocity map imaging spectrometer, the
detection system is comprised of a set of microchannel plates and a Timepix
detector. A fast time-to-digital converter (TDC) is used to enhance the ion
time-of-flight resolution by correlating timestamps registered separately by
the Timepix detector and the TDC. In addition, sub-pixel spatial resolution
(<6 μm) is achieved by the use of a center-of-mass centroiding algorithm. This
performance is achieved while retaining a high event rate (104 per s). The
spectrometer was characterized and used in a proof-of-principle experiment on
strong field dissociative double ionization of carbon dioxide molecules (CO2),
using a 400 kHz repetition rate laser system. The experimental results
demonstrate that the spectrometer can detect multiple ions in coincidence,
making it a valuable tool for studying the fragmentation dynamics of molecules
in strong laser fields