| 1. |
- Drlica-Wagner, A., et al.
(författare)
-
SEARCH FOR GAMMA-RAY EMISSION FROM DES DWARF SPHEROIDAL GALAXY CANDIDATES WITH FERMI-LAT DATA
- 2015
-
Ingår i: Astrophysical Journal Letters. - 2041-8205 .- 2041-8213. ; 809:1
-
Tidskriftsartikel (refereegranskat)abstract
- Due to their proximity, high dark-matter (DM) content, and apparent absence of non-thermal processes, Milky Way dwarf spheroidal satellite galaxies (dSphs) are excellent targets for the indirect detection of DM. Recently, eight new dSph candidates were discovered using the first year of data from the Dark Energy Survey (DES). We searched for gamma-ray emission coincident with the positions of these new objects in six years of Fermi Large Area Telescope data. We found no significant excesses of gamma-ray emission. Under the assumption that the DES candidates are dSphs with DM halo properties similar to the known dSphs, we computed individual and combined limits on the velocity-averaged DM annihilation cross section for these new targets. If the estimated DM content of these dSph candidates is confirmed, they will constrain the annihilation cross section to lie below the thermal relic cross section for DM particles with masses less than or similar to 20 GeV annihilating via the b (b) over bar or pi(+)pi(-) channels.
|
|
| 2. |
- Kastlander, Johan, et al.
(författare)
-
Development of methods to use CdTe detectors in field measurements
- 2006
-
Ingår i: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 41, s. 523-526
-
Tidskriftsartikel (refereegranskat)abstract
- We are currently investigating the possibility to use CdTe detectors for in situ determinations of radionuclide concentration in soil. Buried activity can be reliably determined by a comparison of the count rate in the photo peak and the region between the photo peak and Compton edge. However, the pulse-height spectrum from CdTe detectors is severely deteriorated, due to poor charge collection, in particular for high gamma-ray energies. Our efforts have, therefore, been concentrated on improving the peak to valley ratio for such detectors. A simple, non-discriminating, algorithm for the analysis of output from two amplifiers with different shaping times is described. By means of this algorithm the peak-tovalley ratio for a small planar CdTe detector is improved by more than a factor of six compared to the uncorrected ratio without loss of efficiency.
|
|
| 3. |
- Mohamed, Awaz, et al.
(författare)
-
Securing Nature's Contributions to People requires at least 20%-25% (semi-)natural habitat in human-modified landscapes
- 2024
-
Ingår i: One Earth. - 2590-3330 .- 2590-3322. ; 7:1
-
Tidskriftsartikel (refereegranskat)abstract
- The cascading effects of biodiversity decline on human well-being present a pressing challenge for sustainable development. Conservation efforts often prioritize safeguarding specific species, habitats, or intact ecosystems but overlook biodiversity's fundamental role in providing Nature's Contributions to People (NCP) in human -modified landscapes. Here, we systematically review 154 peer -reviewed studies to estimate the minimum levels of (semi -)natural habitat quantity, quality, and spatial configuration needed in human -modified landscapes to secure functional integrity essential for sustaining NCP provision. We find that the provision of multiple NCP is threatened when (semi -)natural habitat in the landscape falls below an area of 20%- 25% for each km2. Five NCP almost completely disappear below a level of 10% habitat. The exact quantity, quality, and spatial configuration of habitat required depends on local context and specific NCP. Today, about two-thirds of human -modified lands have insufficient (semi -)natural habitat, requiring action for NCP regeneration. Our findings serve as a generic guideline to target conservation actions outside natural areas.
|
|
