First Supra-THz Heterodyne Array Receivers for Astronomy With the SOFIA Observatory

We present the upGREAT THz heterodyne arrays for far-infrared astronomy. The Low Frequency Array (LFA) is designed to cover the 1.9-2.5 THz range using 2x7-pixel waveguide-based HEB mixer arrays in a dual polarization configuration. The High Frequency Array (HFA) will perform observations of the [OI] line at ~4.745 THz using a 7-pixel waveguide-based HEB mixer array. This paper describes the common design for both arrays, cooled to 4.5 K using closed- cycle pulse tube technology. We then show the laboratory and telescope characterization of the first array with its 14 pixels (LFA), which culminated in the successful commissioning in May 2015 aboard the SOFIA airborne observatory observing the [CII] fine structure transition at 1.905 THz. This is the first successful demonstration of astronomical observations with a heterodyne focal plane array above 1 THz and is also the first time high- power closed-cycle coolers for temperatures below 4.5 K are operated on an airborne platform.Comment: accepted for publication in IEEE Transactions on Terahertz Science and Technolog

A search for pair-produced charged Higgs bosons in Z0 decays

A search for pair-produced charged Higgs bosons in decays of the Z0 has been performed using the ALEPH detector at LEP for the decay channels . Searches for two additional decay channels in which cs is replaced by cb were also performed. With 1.17 pb−1 of integrated luminosity, corresponding to about 25 000 hadronic decays of the Z0, the charged Higgs has been excluded at 95% CL in the mass range 7.6 to 43.0 GeV for BR[H± → ντ] = 100%, 8.3 to 40.6 GeV for BR[H±→ντ] = BR[H±→cs] = 50%, and 14.4 to 35.4 GeV for BR[H±→cs] = 100% . With cs replaced by cb, the charged Higgs has been excluded at 95% CL in the mass range 12.0 to 40.7 GeV for BR[H±→ντ] = BR[H±→cb] = 50%, and 16.2 to 35.7 GeV for BR[H±→cb] = 100%

Measurement of alpha-s from the structure of particle clusters produced in hadronic Z decays

Using 106 000 hadronic events obtained with the ALEPH detector at LEP at energies close to the Z resonance peak, the strong coupling constant αs is measured by an analysis of energy-energy correlations (EEC) and the global event shape variables thrust, C-parameter and oblateness. It is shown that the theoretical uncertainties can be significantly reduced if the final state particles are first combined in clusters using a minimum scaled invariant mass cut, Ycut, before these variables are computed. The combined result from all shape variables of pre-clustered events is αs(MZ2 = 0.117±0.005 for a renormalization scale . For μ values between MZ and the b-quark mass, the result changes by −0.009+0.006

Searches for new particles in Z decays using the ALEPH detector

During 1989 and 1990 over 200 000 hadronic and leptonic events, corresponding to about 8.5 pb−1 of data, were collected in a scan of the Z peak using the ALEPH detector at the e+e− collider, LEP. These data, at the highest centre-of-mass energy available to date in e+e− collisions, have allowed a broad range of searches for new particles and new phenomena to be performed in a mass range significantly higher than previously attainable. The searches performed by ALEPH for Higgs bosons, supersymmetric particles and leptoquarks, and for evidence of compositeness are reviewed. No positive signals have been observed but a comprehensive set of mass and coupling limits is presented. Branching ratio limits are given for a number of “rare” Z decays