330 research outputs found
Development of a front end ASIC for Dark Matter directional detection with MIMAC
A front end ASIC (BiCMOS-SiGe 0.35 \mum) has been developed within the
framework of the MIMAC detector project, which aims at directional detection of
non-baryonic Dark Matter. This search strategy requires 3D reconstruction of
low energy (a few keV) tracks with a gaseous \muTPC. The development of this
front end ASIC is a key point of the project, allowing the 3D track
reconstruction. Each ASIC monitors 16 strips of pixels with charge
preamplifiers and their time over threshold is provided in real time by current
discriminators via two serializing LVDS links working at 320 MHz. The charge is
summed over the 16 strips and provided via a shaper. These specifications have
been chosen in order to build an auto triggered electronics. An acquisition
board and the related software were developed in order to validate this
methodology on a prototype chamber. The prototype detector presents an anode
where 2 x 96 strips of pixels are monitored.Comment: 12 pages, 10 figure
Dark matter directional detection with MIMAC
MiMac is a project of micro-TPC matrix of gaseous (He3, CF4) chambers for
direct detection of non-baryonic dark matter. Measurement of both track and
ionization energy will allow the electron-recoil discrimination, while access
to the directionnality of the tracks will open a unique way to distinguish a
geniune WIMP signal from any background. First reconstructed tracks of 5.9 keV
electrons are presented as a proof of concept.Comment: 4 pages, proc. of the 44th Rencontres De Moriond: Electroweak
Interactions And Unified Theories, 7-14 Mar 2009, La Thuile, Ital
MIMAC : A micro-tpc matrix for directional detection of dark matter
Directional detection of non-baryonic Dark Matter is a promising search
strategy for discriminating WIMP events from background. However, this strategy
requires both a precise measurement of the energy down to a few keV and 3D
reconstruction of tracks down to a few mm. To achieve this goal, the MIMAC
project has been developed. It is based on a gaseous micro-TPC matrix, filled
with CF4 and CHF3. The first results on low energy nuclear recoils (H, F)
obtained with a low mono-energetic neutron field are presented. The discovery
potential of this search strategy is discussed and illustrated by a realistic
case accessible to MIMAC.Comment: 6 pages, Proc. of the fifth international symposium on large TPCs for
low energy rare event detection, Paris, France, Dec. 2010. To appear in
Journal of Physic
Conclusion
The outcome of a three-day conference held at the African Studies Centre, Leiden, The Netherlands, in September 1998, this book on the 1997 Kenya general elections is organized in four parts: the direct pre-electoral background; technical and national analysis of the general elections, including the performance of the Electoral Commission, international observation, and the role of the media; regional studies focusing on the grassroots level of Kenyan politics at the Kenya Coast, among the Kenya Somali, in Ukambani, Meru and Embu, Central Province and Nairobi, and Maasailand, among the Kalenjin and the Gusii, in Luo Nyanza, and in Western Province and Trans-Nzoia district; and the Njoro and Laikipia violence in the aftermath of the elections, political developments in 1998 and 1999, and the meaning of electoral politics in Kenya. Contributors: Francis Ang'ila Aywa, Norbert Braakhuis, Marren Akatsa-Bukachi, Fran‡ois Grignon, Charles Hornsby, Joe Kadhi, Peter Mwangi Kagwanja, Karuti Kanyinga, Musambayi Katumanga, Wambui Kimathi, Herv‚ Maupeu, Alamin Mazrui, Kimani Njogu, Adams Oloo, Kenneth Ombongi, Marc-Antoine P‚rouse de Montclos, Ralph-Michael Peters, Marcel RuttenASC – Publicaties niet-programma gebonde
Micromegas micro-TPC for direct Dark Matter search with MIMAC
The MIMAC project is a multi-chamber detector for Dark Matter search, aiming
at measuring both track and ionization with a matrix of micromegas micro-TPC
filled with He3 and CF4. Recent experimental results on the first measurements
of the Helium quenching factor at low energy (1 keV recoil) are presented,
together with the first simulation of the track reconstruction. Recontruction
of track of alpha from Radon impurities is shown as a first proof of concept.Comment: 5 pages, Proc. of the fourth international symposium on large TPCs
for low energy rare event detection, Paris, France, Dec. 2008. To appear in
Journal of Physic
Data acquisition electronics and reconstruction software for directional detection of Dark Matter with MIMAC
Directional detection of galactic Dark Matter requires 3D reconstruction of
low energy nuclear recoils tracks. A dedicated acquisition electronics with
auto triggering feature and a real time track reconstruction software have been
developed within the framework of the MIMAC project of detector. This
auto-triggered acquisition electronic uses embedded processing to reduce data
transfer to its useful part only, i.e. decoded coordinates of hit tracks and
corresponding energy measurements. An acquisition software with on-line
monitoring and 3D track reconstruction is also presented.Comment: 17 pages, 12 figure
Low energy measurements with Helium Micromegas micro-TPC
The measurement of the ionization produced by particles in a medium presents
a great interest in several fields from metrology to particule physics and
cosmology. The ionization quenching factor is defined as the fraction of energy
released by ionisation by a recoil in a medium compared with its kinetic
energy. At low energy, in the range of a few keV, the ionization falls rapidly
and systematic measurement are needed. We have developped an experimental setup
devoted to the measurement of low energy (keV) ionization quenching factor for
the MIMAC project. The ionization produced in the gas has been measured with a
Micromegas detector filled with Helium gas mixture.Comment: Proceedings of the fourth international symposium on large TPCs for
low energy rare event detection, Paris, France, Dec. 2008 To appear in
Journal of Physic
Using time-use diaries to track changing behavior across successive stages of COVID-19 social restrictions
How did people change their behavior over the different phases of the UK COVID-19 restrictions, and how did these changes affect their risk of being exposed to infection? Time-use diary surveys are unique in providing a complete chronicle of daily behavior: 24-h continuous records of the populations’ activities, their social context, and their location. We present results from four such surveys, collected in real time from representative UK samples, both before and at three points over the course of the current pandemic. Comparing across the four waves, we find evidence of substantial changes in the UK population’s behavior relating to activities, locations, and social context. We assign different levels of risk to combinations of activities, locations, and copresence to compare risk-related behavior across successive “lockdowns.” We find evidence that during the second lockdown (November 2020), there was an increase in high-risk behaviors relative to the first (starting March 2020). This increase is shown to be associated with more paid work time in the workplace. At a time when capacity is still limited both in respect of immunization and track–trace technology, governments must continue to rely on changes in people’s daily behaviors to contain the spread of COVID-19 and similar viruses. Time-use diary information of this type, collected in real time across the course of the COVID-19 pandemic, can provide policy makers with information to assess and quantify changes in daily behaviors and the impact they are likely to have on overall behavioral-associated risks
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