Design study of a Fourier spectrometer ellipsoidal mirror reflectometer system Final report

Optimization of interferometer and ellipsoidal reflectometer to measure reflectance of opaque material

Design considerations for thermostatic fin spacecraft temperature control

Design considerations for thermostatic fin spacecraft temperature contro

E(5), X(5), and Prolate to Oblate Shape Phase Transitions in Relativistic Hartree Bogoliubov Theory

Relativistic mean field theory with the NL3 force is used for producing potential energy surfaces (PES) for series of isotopes suggested as exhibiting critical point symmetries. Relatively flat PES are obtained for nuclei showing the E(5) symmetry, while in nuclei corresponding to the X(5) case, PES with a bump are obtained. The PES corresponding to the Pt chain of isotopes suggest a transition from prolate to oblate shapes at 186-Pt.Comment: 21 pages, LaTeX, including 14 .eps figure

A Comparison of Algorithms for the Construction of SZ Cluster Catalogues

We evaluate the construction methodology of an all-sky catalogue of galaxy clusters detected through the Sunyaev-Zel'dovich (SZ) effect. We perform an extensive comparison of twelve algorithms applied to the same detailed simulations of the millimeter and submillimeter sky based on a Planck-like case. We present the results of this "SZ Challenge" in terms of catalogue completeness, purity, astrometric and photometric reconstruction. Our results provide a comparison of a representative sample of SZ detection algorithms and highlight important issues in their application. In our study case, we show that the exact expected number of clusters remains uncertain (about a thousand cluster candidates at |b|> 20 deg with 90% purity) and that it depends on the SZ model and on the detailed sky simulations, and on algorithmic implementation of the detection methods. We also estimate the astrometric precision of the cluster candidates which is found of the order of ~2 arcmins on average, and the photometric uncertainty of order ~30%, depending on flux.Comment: Accepted for publication in A&A: 14 pages, 7 figures. Detailed figures added in Appendi

The Selection Function of SZ Cluster Surveys

We study the nature of cluster selection in Sunyaev-Zel'dovich (SZ) surveys, focusing on single frequency observations and using Monte Carlo simulations incorporating instrumental effects, primary cosmic microwave background (CMB) anisotropies and extragalactic point sources. Clusters are extracted from simulated maps with an optimal, multi-scale matched filter. We introduce a general definition for the survey selection function that provides a useful link between an observational catalog and theoretical predictions. The selection function defined over the observed quantities of flux and angular size is independent of cluster physics and cosmology, and thus provides a useful characterization of a survey. Selection expressed in terms of cluster mass and redshift, on the other hand, depends on both cosmology and cluster physics. We demonstrate that SZ catalogs are not simply flux limited, and illustrate how incorrect modeling of the selection function leads to biased estimates of cosmological parameters. The fact that SZ catalogs are not flux limited complicates survey ``calibration'' by requiring more detailed information on the relation between cluster observables and cluster mass.Comment: Accepted for publication in Astronomy & Astrophysics, 11 pages, 7 figure

Constraining dark energy with Sunyaev-Zel'dovich cluster surveys

We discuss the prospects of constraining the properties of a dark energy component, with particular reference to a time varying equation of state, using future cluster surveys selected by their Sunyaev-Zel'dovich effect. We compute the number of clusters expected for a given set of cosmological parameters and propogate the errors expected from a variety of surveys. In the short term they will constrain dark energy in conjunction with future observations of type Ia supernovae, but may in time do so in their own right.Comment: 5 pages, 3 figures, 1 table, version accepted for publication in PR

Detection of a CMB decrement towards a cluster of mJy radiosources

We present the results of radio, optical and near-infrared observations of the field of TOC J0233.3+3021, a cluster of milliJansky radiosources from the TexOx Cluster survey. In an observation of this field with the Ryle Telescope (RT) at 15 GHz, we measure a decrement in the cosmic microwave background (CMB) of $-675 \pm 95 \mu$Jy on the RT's $\approx$ 0.65 k$\lambda$ baseline. Using optical and infrared imaging with the McDonald 2.7-m Smith Reflector, Calar Alto 3.5-m telescope and UKIRT, we identify the host galaxies of five of the radiosources and measure magnitudes of $R \approx 24$, $J \approx 20$, $K \approx 18$. The CMB decrement is consistent with the Sunyaev-Zel'dovich (SZ) effect of a massive cluster of galaxies, which if modelled as a spherical King profile of core radius $\theta_C = 20^{\prime\prime}$ has a central temperature decrement of $900 \mu$K. The magnitudes and colours of the galaxies are consistent with those of old ellipticals at $z \sim 1$. We therefore conclude that TOC J0233.3+3021 is a massive, high redshift cluster. These observations add to the growing evidence for a significant population of massive clusters at high redshift, and demonstrate the effectiveness of combining searches for AGN `signposts' to clusters with the redshift-independence of the SZ effect.Comment: Six pages; accepted for publication in MNRAS. Version with full-resolution UV plot available from http://www.mrao.cam.ac.uk/~garret/MB185.p

Search for the electric dipole excitations to the 3s1/2⊗[21+⊗31−]3s_{1/2} \otimes [2^{+}_{1} \otimes 3^{-}_{1}] multiplet in 117^{117}Sn

The odd-mass $^{117}$Sn nucleus was investigated in nuclear resonance fluorescence experiments up to an endpoint energy of the incident photon spectrum of 4.1 MeV at the bremsstrahlung facility of the Stuttgart University. More than 50 mainly hitherto unknown levels were found. From the measurement of the scattering cross sections model independent absolute electric dipole excitation strengths were extracted. The measured angular distributions suggested the spins of 11 excited levels. Quasi-particle phonon model calculations including a complete configuration space were performed for the first time for a heavy odd-mass spherical nucleus. These calculations give a clear insight in the fragmentation and distribution of the $E1$, $M1$, and $E2$ excitation strength in the low energy region. It is proven that the $1^{-}$ component of the two-phonon $[2^{+}_{1} \otimes 3^{-}_{1}]$ quintuplet built on top of the $1/2^{+}$ ground state is strongly fragmented. The theoretical calculations are consistent with the experimental data.Comment: 10 pages, 5 figure