705 research outputs found
Experimental study of a liquid Xenon PET prototype module
A detector using liquid Xenon in the scintillation mode is studied for
Positron Emission Tomography (PET). The specific design aims at taking full
advantage of the liquid Xenon properties. It does feature a promising
insensitive to any parallax effect. This work reports on the performances of
the first LXe prototype module, equipped with a position sensitive PMT
operating in the VUV range (178 nm).Comment: Proc. of the 7th International Workshops on Radiation Imaging
Detectors (IWORID-7), Grenoble, France 4-7 July 200
A Digitally Calibrated 12 bits 25 MS/s Pipelined ADC with a 3 input multiplexer for CALICE Integrated Readout
The necessity of full integrated electronics readout for the next ILC ECAL presents many challenges for low power mixed signal design. The analog to digital converter is a critical stage for the system going from the very front-end stages to digital memories. We present here a high speed converter configuration designed to multiplex 3 analog channels through one analog to digital converter. It is a first step for a multiplexed 64 channel design. A CMOS 0.35ÎĽm process is used. The dynamic range is 2V over a 3.3V power supply, and the total power dissipation at 25 MHz is approximately 40mW. An analog power management is included to allow a fast switching into a standby mode that reduces the DC power dissipation by a ratio of three orders of magnitude (1/1000)
Experimental results and first 22Na source image reconstruction by two prototype modules in coincidence of a liquid xenon positron emission tomograph for small animal imaging
International audienceA detector with a very specific design using liquid Xenon (LXe) in the scintillation mode is studied for Positron Emission Tomography (PET) of small animals. Two prototype modules equipped with Position Sensitive Photo Multiplier Tubes (PSPMTs) operating in the VUV range (178 nm) and at 165 K were built and studied in coincidence. This paper reports on energy, time and spatial resolution capabilities of this experimental test bench. Furthermore, these experimental results were used to perform the first image reconstruction of a 22Na source placed in the experimental setup
Design of High Dynamic Range Digital to Analog Converters for the Calibration of the CALICE Si-W Ecal readout electronics
The ILC ECAL front-end chip will integrate many functions of the readout electronics including a DAC dedicated to calibration. We present two versions of DAC with respectively 12 and 14 bits, designed in a CMOS 0.35ÎĽm process. Both are based on segmented arrays of switched capacitors controlled by a Dynamic Element Matching (DEM) algorithm. A full differential architecture is used, and the amplifiers can be turned into a standby mode reducing the power dissipation. The 12 bit DAC features an INL lower than 0.3 LSB at 5MHz, and dissipates less than 7mW. The 14 bit DAC is an improved version of the 12 bit design
Global unions: chasing the dream or building the reality?
This article takes as its theme the global restructuring of capital and its impact on worker organization. It argues for a reassertion of class in any analysis of global solidarity, and assesses the opportunities and barriers to effective global unionization. Rooted in the UK experience, the article analyzes the impact of the European social dimension on trade unions, before taking the discussion into a global dimension. It concludes by suggesting that there are reasons for cautious optimism in terms of solidarity building, despite difficult historical legacies and the common replacement of action with rhetoric
A liquid Xenon Positron Emission Tomograph for small animal imaging : first experimental results of a prototype cell
A detector using liquid Xenon (LXe) in the scintillation mode is studied for
Positron Emission Tomography (PET) of small animals. Its specific design aims
at taking full advantage of the Liquid Xenon scintillation properties. This
paper reports on energy, time and spatial resolution capabilities of the first
LXe prototype module equipped with a Position Sensitive Photo- Multiplier tube
(PSPMT) operating in the VUV range (178 nm) and at 165 K. The experimental
results show that such a LXe PET configuration might be a promising solution
insensitive to any parallax effect.Comment: 34 pages, 18 pages, to appear in NIM
Critical values for Lawshe's content validity ratio: revisiting the original methods of calculation
YesThe content validity ratio originally proposed by Lawshe is widely used to quantify content validity and yet methods used to calculate the original critical values were never reported. Methods for original calculation of critical values are suggested along with tables of exact binomial probabilities
Constructing transnational solidarity: the role of campaign governance
Our inductive study of two transnational labour solidarity efforts focuses on the role of campaign governance. Specifically, we study contrasting campaign strategies, tactics and coalition structures in campaigns by two global union federations, UNI Global Union and the IUF, contextualized in terms of how these campaigns unfolded in India. Our contribution consists of two arguments. The first is that a degree of internal consistency amongst different campaign elements is important for success, and the second is that a mode of articulation that allows for local concerns in affiliate countries to find voice in global campaigns is more likely to result in concrete gains at the local level
A low power and low signal 4 bit 50MS/s double sampling pipelined ADC for monolithie active pixel sensors
A 4 bit very low power and low incoming signal analog to digital converter (ADC) using a double sampling switched capacitor technique, designed for use in CMOS monolithic active pixels sensor readout, has been implemented in 0.35ÎĽm CMOS technology. A non-resetting sample and hold stage is integrated to amplify the incoming signal by 4. This first stage compensates both the amplifier offset effect and the input common mode voltage fluctuations. The converter is composed of a 2.5 bit pipeline stage followed by a 2 bit flash stage. This prototype consists of 4 ADC double-channels; each one is sampling at 50MS/s and dissipates only 2.6mW at 3.3V supply voltage. A bias pulsing stage is integrated in the circuit. Therefore, the analog part is switched OFF or ON in less than 1ÎĽs. The size for the layout is 80ÎĽm*0.9mm. This corresponds to the pitch of 4 pixel columns, each one is 20ÎĽm wide
Automating Access Control Logics in Simple Type Theory with LEO-II
Garg and Abadi recently proved that prominent access control logics can be
translated in a sound and complete way into modal logic S4. We have previously
outlined how normal multimodal logics, including monomodal logics K and S4, can
be embedded in simple type theory (which is also known as higher-order logic)
and we have demonstrated that the higher-order theorem prover LEO-II can
automate reasoning in and about them. In this paper we combine these results
and describe a sound and complete embedding of different access control logics
in simple type theory. Employing this framework we show that the off the shelf
theorem prover LEO-II can be applied to automate reasoning in prominent access
control logics.Comment: ii + 20 page
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