27 research outputs found
A background free double beta decay experiment
We present a new detection scheme for rejecting backgrounds in neutrino less
double beta decay experiments. It relies on the detection of Cherenkov light
emitted by electrons in the MeV region. The momentum threshold is tuned to
reach a good discrimination between background and good events. We consider
many detector concepts and a range of target materials. The most promising is a
high-pressure 136Xe emitter for which the required energy threshold is easily
adjusted. Combination of this concept and a high pressure Time Projection
Chamber could provide an optimal solution. A simple and low cost effective
solution is to use the Spherical Proportional Counter that provides two delayed
signals from ionization and Cherenkov light.
In solid-state double beta decay emitters, because of their higher density,
the considered process is out of energy range. An alternative solution could be
the development of double decay emitters with lower density by using for
instance the aerogel technique. It is surprising that a technology used for
particle identification in high-energy physics becomes a powerful tool for
rejecting backgrounds in such low-energy experiments
Fast Timing for High-Rate Environments with Micromegas
The current state of the art in fast timing resolution for existing
experiments is of the order of 100 ps on the time of arrival of both charged
particles and electromagnetic showers. Current R&D on charged particle timing
is approaching the level of 10 ps but is not primarily directed at sustained
performance at high rates and under high radiation (as would be needed for
HL-LHC pileup mitigation). We demonstrate a Micromegas based solution to reach
this level of performance. The Micromegas acts as a photomultiplier coupled to
a Cerenkov-radiator front window, which produces sufficient UV photons to
convert the ~100 ps single-photoelectron jitter into a timing response of the
order of 10-20 ps per incident charged particle. A prototype has been built in
order to demonstrate this performance. The first laboratory tests with a
pico-second laser have shown a time resolution of the order of 27 ps for ~50
primary photoelectrons, using a bulk Micromegas readout.Comment: MPGD2015 (4th Conference on Micro-Pattern Gaseous Detectors, Trieste,
Italy, 12 - 15 October, 2015). 5 pages, 8 figure
New neutron detector based on Micromegas technology for ADS projects
A new neutron detector based on Micromegas technology has been developed for the measurement of the simulated neutron spectrum in the ADS project. After the presentation of simulated neutron spectra obtained in the interaction of 140 MeV protons with the spallation target inside the TRIGA core, a full description of the new detector configuration is given. The advantage of this detector compared to conventional neutron flux detectors and the results obtained with the first prototype at the CELINA 14 MeV neutron source facility at CEA-Cadarache are presented. The future developments of operational Piccolo-Micromegas for fast neutron reactors are also described
A large area 100 channel Picosec Micromegas detector with sub 20 ps time resolution
The PICOSEC Micromegas precise timing detector is based on a Cherenkov
radiator coupled to a semi-transparent photocathode and a Micromegas
amplification structure. The first proof of concept single-channel small area
prototype was able to achieve time resolution below 25 ps. One of the crucial
aspects in the development of the precise timing gaseous detectors applicable
in high-energy physics experiments is a modular design that enables large area
coverage. The first 19-channel multi-pad prototype with an active area of
approximately 10 cm suffered from degraded timing resolution due to the
non-uniformity of the preamplification gap. A new 100 cm detector module
with 100 channels based on a rigid hybrid ceramic/FR4 Micromegas board for
improved drift gap uniformity was developed. Initial measurements with 80 GeV/c
muons showed improvements in timing response over measured pads and a time
resolution below 25 ps. More recent measurements with a new thinner drift gap
detector module and newly developed RF pulse amplifiers show that the
resolution can be enhanced to a level of 17~ps. This work will present the
development of the detector from structural simulations, design, and beam test
commissioning with a focus on the timing performance of a thinner drift gap
detector module in combination with new electronics using an automated timing
scan method
Towards robust PICOSEC Micromegas precise timing detectors
The PICOSEC Micromegas (MM) detector is a precise timing gaseous detector
consisting of a Cherenkov radiator combined with a photocathode and a MM
amplifying structure. A 100-channel non-resistive PICOSEC MM prototype with
10x10 cm^2 active area equipped with a Cesium Iodide (CsI) photocathode
demonstrated a time resolution below 18 ps. The objective of this work is to
improve the PICOSEC MM detector robustness aspects; i.e. integration of
resistive MM and carbon-based photocathodes; while maintaining good time
resolution. The PICOSEC MM prototypes have been tested in laboratory conditions
and successfully characterised with 150 GeV/c muon beams at the CERN SPS H4
beam line. The excellent timing performance below 20 ps for an individual pad
obtained with the 10x10 cm^2 area resistive PICOSEC MM of 20 MOhm/sq showed no
significant time resolution degradation as a result of adding a resistive
layer. A single-pad prototype equipped with a 12 nm thick Boron Carbide (B4C)
photocathode presented a time resolution below 35 ps; opening up new
possibilities for detectors with robust photocathodes. The results made the
concept more suitable for the experiments in need of robust detectors with good
time resolution
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Research and Design of a Routing Protocol in Large-Scale Wireless Sensor Networks
无线传感器网络,作为全球未来十大技术之一,集成了传感器技术、嵌入式计算技术、分布式信息处理和自组织网技术,可实时感知、采集、处理、传输网络分布区域内的各种信息数据,在军事国防、生物医疗、环境监测、抢险救灾、防恐反恐、危险区域远程控制等领域具有十分广阔的应用前景。 本文研究分析了无线传感器网络的已有路由协议,并针对大规模的无线传感器网络设计了一种树状路由协议,它根据节点地址信息来形成路由,从而简化了复杂繁冗的路由表查找和维护,节省了不必要的开销,提高了路由效率,实现了快速有效的数据传输。 为支持此路由协议本文提出了一种自适应动态地址分配算——ADAR(AdaptiveDynamicAddre...As one of the ten high technologies in the future, wireless sensor network, which is the integration of micro-sensors, embedded computing, modern network and Ad Hoc technologies, can apperceive, collect, process and transmit various information data within the region. It can be used in military defense, biomedical, environmental monitoring, disaster relief, counter-terrorism, remote control of haz...学位:工学硕士院系专业:信息科学与技术学院通信工程系_通信与信息系统学号:2332007115216
Georges Charpak (1924-2010)
ObituaryInternational audiencePhysicist who transformed the measurement of high-energy particle
Colloquium for the 85th Birthday of Georges Charpak
Georges Charpak and the invention and development of particle detector