An ultra-bright atom laser

We present a novel, ultra-bright atom-laser and ultra-cold thermal atom beam. Using rf-radiation we strongly couple the magnetic hyperfine levels of 87Rb atoms in a magnetically trapped Bose-Einstein condensate. At low rf-frequencies gravity opens a small hole in the trapping potenital and a well collimated, extremely bright atom laser emerges from just below the condensate. As opposed to traditional atom lasers based on weak coupling, this technique allows us to outcouple atoms at an arbitrarily large rate. We demonstrate an increase in flux per atom in the BEC by a factor of sixteen compared to the brightest quasi-continuous atom laser. Furthermore, we produce by two orders of magnitude the coldest thermal atom beam to date (200 nK).Comment: 20 pages, 9 figures, supplementary material online at http://www.bec.g

When Political Will Is Not Enough: Jails, Communities, and Persons With Mental Health Disorders

This article describes a project that generated the recommendations of a panel of experts regarding the jail as a venue for the delivery of behavioral health care services. The project was a component of the MacArthur Foundation’s Safety and Justice Challenge initiative, which seeks to address over-incarceration by changing the way jails are conceptualized and used. The recommendations were grounded largely in the sequential intercept model that rests on two core principles: minimize the inappropriate penetration of persons with mental illness into the criminal justice system and recognize that the community is the unit of analysis to address criminal justice–mental health problems successfully. Other topics presented in the context of the initiative included bringing the community to scale, jail diversion, the limits of jail responsibility, and the Affordable Care Act’s role in providing insurance coverage for detainees

Crack Front Waves and the dynamics of a rapidly moving crack

Crack front waves are localized waves that propagate along the leading edge of a crack. They are generated by the interaction of a crack with a localized material inhomogeneity. We show that front waves are nonlinear entities that transport energy, generate surface structure and lead to localized velocity fluctuations. Their existence locally imparts inertia, which is not incorporated in current theories of fracture, to initially "massless" cracks. This, coupled to crack instabilities, yields both inhomogeneity and scaling behavior within fracture surface structure.Comment: Embedded Latex file including 4 figure

Temperatures of Fragment Kinetic Energy Spectra

Multifragmentation reactions without large compression in the initial state (proton-induced reactions, reverse-kinematics, projectile fragmentation) are examined, and it is verified quantitatively that the high temperatures obtained from fragment kinetic energy spectra and lower temperatures obtained from observables such as level population or isotope ratios can be understood in a common framework.Comment: LaTeX, 7 pages, 2 figures available from autho

Evolution of the UV Excess in Early-Type Galaxies

We examine the UV emission from luminous early-type galaxies as a function of redshift. We perform a stacking analysis using Galaxy Evolution Explorer (GALEX) images of galaxies in the NOAO Deep Wide Field Survey (NDWFS) Bo\"otes field and examine the evolution in the UV colors of the average galaxy. Our sample, selected to have minimal ongoing star formation based on the optical to mid-IR SEDs of the galaxies, includes 1843 galaxies spanning the redshift range $0.05\leq z\leq0.65$. We find evidence that the strength of the UV excess decreases, on average, with redshift, and our measurements also show moderate disagreement with previous models of the UV excess. Our results show little evolution in the shape of the UV continuum with redshift, consistent either with the binary model for the formation of Extreme Horizontal Branch (EHB) stars or with no evolution in EHB morphology with look-back time. However, the binary formation model predicts that the strength of the UV excess should also be relatively constant, in contradiction with our measured results. Finally, we see no significant influence of a galaxy's environment on the strength of its UV excess.Comment: 30 pages, 10 figures; accepted by ApJ. Modified from original version to reflect referee's comment

SDTrimSP Simulations of Solar Wind Sputtering on Mercury: A Sensitivity Study to Establish a Best-Practice

Understanding the role solar wind (SW) ions play on surface sputtering of Mercury is critical to any exosphere model. The most common models use binary collision approximation (BCA) tools such as SDTrimSP. However, this state-of-the-art tool has many user-specific inputs and that are not immediately clear for more complex substrates such as minerals on celestial surfaces. These include surface binding energies, SW compositions, static vs. dynamic, and impact energy. Previous research has not kept these parameters consistent, making it unclear how sensitive sputtering behavior is to these parameters. As such, we have conducted a detailed sensitivity study into SDTrimSP parameters for simulating SW impacts. We have considered how several important simulation choices affect sputtering yields, composition, energy distribution, and damage. Results show that sputtering behavior is highly dependent on these parameters and can be used to establish a best practice methodology for SDTrimSP

Time-of-flight mass measurements of neutron-rich chromium isotopes up to N = 40 and implications for the accreted neutron star crust

We present the mass excesses of 59-64Cr, obtained from recent time-of-flight nuclear mass measurements at the National Superconducting Cyclotron Laboratory at Michigan State University. The mass of 64Cr is determined for the first time, with an atomic mass excess of -33.48(44) MeV. We find a significantly different two-neutron separation energy S2n trend for neutron-rich isotopes of chromium, removing the previously observed enhancement in binding at N=38. Additionally, we extend the S2n trend for chromium to N=40, revealing behavior consistent with the previously identified island of inversion in this region. We compare our results to state-of-the-art shell-model calculations performed with a modified Lenzi-Nowacki-Poves-Sieja interaction in the fp shell, including the g9/2 and d5/2 orbits for the neutron valence space. We employ our result for the mass of 64Cr in accreted neutron star crust network calculations and find a reduction in the strength and depth of electron-capture heating from the A=64 isobaric chain, resulting in a cooler than expected accreted neutron star crust. This reduced heating is found to be due to the >1-MeV reduction in binding for 64Cr with respect to values from commonly used global mass models.Comment: Accepted to Physical Review