A Fluctuation Analysis of the Bolocam 1.1mm Lockman Hole Survey

We perform a fluctuation analysis of the 1.1mm Bolocam Lockman Hole Survey, which covers 324 square arcmin to a very uniform point source-filtered RMS noise level of 1.4 mJy/beam. The fluctuation analysis has the significant advantage of utilizing all of the available data. We constrain the number counts in the 1-10 mJy range, and derive significantly tighter constraints than in previous work: the power-law index is 2.7 (+0.18, -0.15), while the amplitude is equal to 1595 (+85,-238) sources per mJy per square degree, or N(>1 mJy) = 940 (+50,-140) sources/square degree (95% confidence). Our results agree extremely well with those derived from the extracted source number counts by Laurent et al (2005). Our derived normalization is about 2.5 times smaller than determined by MAMBO at 1.2mm by Greve et al (2004). However, the uncertainty in the normalization for both data sets is dominated by the systematic (i.e., absolute flux calibration) rather than statistical errors; within these uncertainties, our results are in agreement. We estimate that about 7% of the 1.1mm background has been resolved at 1 mJy.Comment: To appear in the Astrophysical Journal; 22 pages, 9 figure

The cryomechanical design of MUSIC: a novel imaging instrument for millimeter-wave astrophysics at the Caltech Submillimeter Observatory

MUSIC (Multicolor Submillimeter kinetic Inductance Camera) is a new facility instrument for the Caltech Submillimeter Observatory (Mauna Kea, Hawaii) developed as a collaborative effect of Caltech, JPL, the University of Colorado at Boulder and UC Santa Barbara, and is due for initial commissioning in early 2011. MUSIC utilizes a new class of superconducting photon detectors known as microwave kinetic inductance detectors (MKIDs), an emergent technology that offers considerable advantages over current types of detectors for submillimeter and millimeter direct detection. MUSIC will operate a focal plane of 576 spatial pixels, where each pixel is a slot line antenna coupled to multiple detectors through on-chip, lumped-element filters, allowing simultaneously imaging in four bands at 0.86, 1.02, 1.33 and 2.00 mm. The MUSIC instrument is designed for closed-cycle operation, combining a pulse tube cooler with a two-stage Helium-3 adsorption refrigerator, providing a focal plane temperature of 0.25 K with intermediate temperature stages at approximately 50, 4 and 0.4 K for buffering heat loads and heat sinking of optical filters. Detector readout is achieved using semi-rigid coaxial cables from room temperature to the focal plane, with cryogenic HEMT amplifiers operating at 4 K. Several hundred detectors may be multiplexed in frequency space through one signal line and amplifier. This paper discusses the design of the instrument cryogenic hardware, including a number of features unique to the implementation of superconducting detectors. Predicted performance data for the instrument system will also be presented and discussed

Use of the PIXEL method to investigate gas adsorption in metal–organic frameworks

PIXEL has been used to perform calculations of adsorbate-adsorbent interaction energies between a range of metal–organic frameworks (MOFs) and simple guest molecules. Interactions have been calculated for adsorption between MOF-5 and Ar, H(2), and N(2); Zn(2)(BDC)(2)(TED) (BDC = 1,4-benzenedicarboxylic acid, TED = triethylenediamine) and H(2); and HKUST-1 and CO(2). The locations of the adsorption sites and the calculated energies, which show differences in the Coulombic or dispersion characteristic of the interaction, compare favourably to experimental data and literature energy values calculated using density functional theory