Cosmogenic activation of xenon and copper

Rare event search experiments using liquid xenon as target and detection medium require ultra-low background levels to fully exploit their physics potential. Cosmic ray induced activation of the detector components and, even more importantly, of the xenon itself during production, transportation and storage at the Earth's surface, might result in the production of radioactive isotopes with long half-lives, with a possible impact on the expected background. We present the first dedicated study on the cosmogenic activation of xenon after 345 days of exposure to cosmic rays at the Jungfraujoch research station at 3470m above sea level, complemented by a study of copper which has been activated simultaneously. We have directly observed the production of 7Be, 101Rh, 125Sb, 126I and 127Xe in xenon, out of which only 125Sb could potentially lead to background for a multi-ton scale dark matter search. The production rates for five out of eight studied radioactive isotopes in copper are in agreement with the only existing dedicated activation measurement, while we observe lower rates for the remaining ones. The specific saturation activities for both samples are also compared to predictions obtained with commonly used software packages, where we observe some underpredictions, especially for xenon activation.Comment: 9 pages, 11 figure

Dark matter sensitivity of multi-ton liquid xenon detectors

We study the sensitivity of multi ton-scale time projection chambers using a liquid xenon target, e.g., the proposed DARWIN instrument, to spin-independent and spin-dependent WIMP-nucleon scattering interactions. Taking into account realistic backgrounds from the detector itself as well as from neutrinos, we examine the impact of exposure, energy threshold, background rejection efficiency and energy resolution on the dark matter sensitivity. With an exposure of 200 t x y and assuming detector parameters which have been already demonstrated experimentally, spin-independent cross sections as low as $2.5 \times 10^{-49}$ cm$^2$ can be probed for WIMP masses around 40 GeV/$c^2$. Additional improvements in terms of background rejection and exposure will further increase the sensitivity, while the ultimate WIMP science reach will be limited by neutrinos scattering coherently off the xenon nuclei.Comment: 21 pages, 8 Figures; matches version accepted by JCA

The Information Service Evaluation (ISE) Model

Information services are an inherent part of our everyday life. Especially since ubiquitous cities are being developed all over the world their number is increasing even faster. They aim at facilitating the production of information and the access to the needed information and are supposed to make life easier. Until today many different evaluation models (among others, TAM, TAM 2, TAM 3, UTAUT and MATH) have been developed to measure the quality and acceptance of these services. Still, they only consider subareas of the whole concept that represents an information service. As a holistic and comprehensive approach, the ISE Model studies five dimensions that influence adoption, use, impact and diffusion of the information service: information service quality, information user, information acceptance, information environment and time. All these aspects have a great impact on the final grading and of the success (or failure) of the service. Our model combines approaches, which study subjective impressions of users (e.g., the perceived service quality), and user-independent, more objective approaches (e.g., the degree of gamification of a system). Furthermore, we adopt results of network economics, especially the "Success breeds success"-principle

Ecologically Inspired Design of Green Roof Retrofit

Green roofs are becoming popular in the United States for their runoff and energy reduction abilities. However, current designs have high installation costs, heavy load-bearing requirements, and restrictions to low-sloped roofs. We designed a novel retrofit technology, the green cloak, which uses fast-growing vine species and a trellis to suspend vegetation above a roof. We conducted field experiments, prototype testing, and mathematical modeling to determine the effect of the green cloak on stormwater runoff and indoor summertime building temperature reduction. We assessed energy and monetary cost-benefits. The green cloak reduced July indoor building temperature by 11.3°C which saved 73% of cooling energy costs. The green cloak delayed the peak storm runoff from a 0.15mm/min storm by 100 minutes. The green cloak costs 38% less than a green roof. The green cloak demonstrated great potential for mitigating runoff impacts of impervious surfaces, reducing summer temperatures of buildings, and creating urban greenery

Background Measurements in the Gran Sasso Underground Laboratory

The gamma background flux below 3000 keV in the Laboratori Nazionali del Gran Sasso (LNGS), Italy, has been measured using a 3" diameter NaI(Tl) detector at different underground positions: In hall A, hall B, the interferometer tunnel, and inside the Large Volume Detector (LVD). The integrated flux is 0.3--0.4 s$^{-1}$cm$^{-2}$ at the first three locations, and is lower by two orders of magnitude inside LVD. With the help of Monte Carlo simulations for every location, the contribution of the individual primordial isotopes to the background has been determined. Using an 11" diameter NaI(Tl) detector, the background neutron flux in the LNGS interferometer tunnel has been estimated. Within the uncertainties, the result agrees with those from other neutron measurements in the main halls.Comment: 6 pages, 6 figures, accepted versio

2014 Causes Count: The Economic Power of California\u27s Nonprofit Sector

Causes Count describes, in economic terms, the stunning size, variety, activities and impact of California’s large and diverse nonpro t sector. The research was conducted by The Caster Family Center for Nonprofit and Philanthropic Research at the University of San Diego and was guided by an advisory panel of more than 30 leaders throughout California. This study synthesizes multiple sources of data to generate the most complete picture of the power of California’s nonprofit sector to date. The research identifies and documents trends in the financial health of nonprofits, employment, volunteerism, foundation grantmaking, and civic engagement, as well as provides insight into what may be in store for California’s nonprofit sector in the future.https://digital.sandiego.edu/npi-stateofnpca/1001/thumbnail.jp

State of Nonprofits Annual Report: 2015

For nearly a decade, The Caster Family Center for Nonprofit and Philanthropic Research (Caster Center) has gathered and analyzed data to tell the story of San Diego’s diverse, growing, and influential nonprofit and philanthropic sector. This year’s State of Nonprofits and Philanthropy report documents the increased economic impact of the sector as revenue, assets, and employment continue to grow. Furthermore, our State of Nonprofit Quarterly Index (SONP) and survey data from nonprofit leaders indicate that, overall, the sector is moving in a positive direction.https://digital.sandiego.edu/npi-stateofnp/1002/thumbnail.jp

2013 Study on Children of Seriously Wounded Service Members

Over the course of one year, researchers from The Caster Family Center for Nonprofit and Philanthropic at the University of San Diego interviewed a total of 125 participants, including seriously wounded service members, their spouses and children, as well as military, civilian and nonprofit professionals who work with this population. The study included two phases to ensure a comprehensive understanding around the population and its unfulfilled needs: The first phase focused on understanding the specific needs of children of seriously wounded service members through interviews, focus groups, and reviews of existing research; the second phase focused on an assessment of government and nonprofit programs available to identify gaps that exist.https://digital.sandiego.edu/npi-military/1003/thumbnail.jp