Limits on the production of scalar leptoquarks from Z (0) decays at LEP

A search has been made for pairs and for single production of scalar leptoquarks of the first and second generations using a data sample of 392000 Z0 decays from the DELPHI detector at LEP 1. No signal was found and limits on the leptoquark mass, production cross section and branching ratio were set. A mass limit at 95% confidence level of 45.5 GeV/c2 was obtained for leptoquark pair production. The search for the production of a single leptoquark probed the mass region above this limit and its results exclude first and second generation leptoquarks D0 with masses below 65 GeV/c2 and 73 GeV/c2 respectively, at 95% confidence level, assuming that the D0lq Yukawa coupling alpha(lambda) is equal to the electromagnetic one. An upper limit is also given on the coupling alpha(lambda) as a function of the leptoquark mass m(D0)

The Soft X-ray Imager (SXI) on the SMILE Mission

The Soft X-ray Imager (SXI) is part of the scientific payload of the Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) mission. SMILE is a joint science mission between the European Space Agency (ESA) and the Chinese Academy of Sciences (CAS) and is due for launch in 2025. SXI is a compact X-ray telescope with a wide field-of-view (FOV) capable of encompassing large portions of Earth’s magnetosphere from the vantage point of the SMILE orbit. SXI is sensitive to the soft X-rays produced by the Solar Wind Charge eXchange (SWCX) process produced when heavy ions of solar wind origin interact with neutral particles in Earth’s exosphere. SWCX provides a mechanism for boundary detection within the magnetosphere, such as the position of Earth’s magnetopause, because the solar wind heavy ions have a very low density in regions of closed magnetic field lines. The sensitivity of the SXI is such that it can potentially track movements of the magnetopause on timescales of a few minutes and the orbit of SMILE will enable such movements to be tracked for segments lasting many hours. SXI is led by the University of Leicester in the United Kingdom (UK) with collaborating organisations on hardware, software and science support within the UK, Europe, China and the United States

The Soft X-ray Imager (SXI) on the SMILE Mission

The Soft X-ray Imager (SXI) is part of the scientific payload of the Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) mission. SMILE is a joint science mission between the European Space Agency (ESA) and the Chinese Academy of Sciences (CAS) and is due for launch in 2025. SXI is a compact X-ray telescope with a wide field-of-view (FOV) capable of encompassing large portions of Earth’s magnetosphere from the vantage point of the SMILE orbit. SXI is sensitive to the soft X-rays produced by the Solar Wind Charge eXchange (SWCX) process produced when heavy ions of solar wind origin interact with neutral particles in Earth’s exosphere. SWCX provides a mechanism for boundary detection within the magnetosphere, such as the position of Earth’s magnetopause, because the solar wind heavy ions have a very low density in regions of closed magnetic field lines. The sensitivity of the SXI is such that it can potentially track movements of the magnetopause on timescales of a few minutes and the orbit of SMILE will enable such movements to be tracked for segments lasting many hours. SXI is led by the University of Leicester in the United Kingdom (UK) with collaborating organisations on hardware, software and science support within the UK, Europe, China and the United States

The hard X-ray performance of pixelated CdTe-based detectors using Monte Carlo and ab initio simulations

The performance of pixelated semiconductor radiation detectors based on cadmium telluride (CdTe) were investigated using experimental, Monte Carlo and ab initio methods for their detection of hard X-rays while operating at room temperature. To achieve the imaging, photon-counting and energy-resolving requirements of CdTe-based detector applications, pixelated detector designs are commonly used. Charge sharing and fluorescence interference as a result of pixelation, and distortions of the electric field profile, severely impact the performance in these detectors. Inhomogeneities and defects in the crystals due to on-going growth challenges of CdTe also limit performance. The photon-counting and spectral performance of a novel high-flux capable CdZnTe (HFCdZnTe) is measured at photon energies 6 to 140 keV and compared with a gold-standard CdTe detector. Factors contributing to the energy resolution of charge sharing events such as charge loss and fluorescence are quantified. A fully spectroscopic Monte Carlo (MC) detector model is developed and shown to accurately predict the rate of charge sharing in these detectors. By comparing experimental and MC simulated data, a number of quantities related to performance such as the size of the electron charge clouds, the strength of the electric field and the Zn concentration in the HF-CdZnTe material are estimated. Using density functional theory (DFT), alloys of CdTe that are in early stages of development for radiation detection are studied from ab initio. The formation of the cadmium vacancy defect (VCd) in Cd1−xMnxTe and Cd1−xMgxTe crystals is studied and compared with the more well established Cd1−xZnxTe system. The VCd formation energy as a function of alloy concentration x is calculated to help understand the defect concentrations and resistivity in these alloys. The effect the addition of Mn and Mg have on the physical properties of CdTe, including phase transitions of their lattices, are also determined.</p

Modelling spectroscopic performance of pixelated semiconductor detectors through Monte-Carlo simulation

When choosing or designing a detector for a particular application, a complete understanding of the expected response is vital. Parameters such as quantum efficiency, spatial resolution, signal-to-noise ratio, count rate capability and spectral resolution all play a part in the suitability of a detector. These parameters are not necessarily independent, and in many cases an improvement in one parameter can only be achieved with deterioration of another.</p

Charge Sharing and Charge Loss in High-Flux Capable Pixelated CdZnTe Detectors

Cadmium zinc telluride (CdZnTe) detectors are known to suffer from polarization effects under high photon flux due to poor hole transport in the crystal material. This has led to the development of a high-flux capable CdZnTe material (HF-CdZnTe). Detectors with the HF-CdZnTe material have shown promising results at mitigating the onset of the polarization phenomenon, likely linked to improved crystal quality and hole carrier transport. Better hole transport will have an impact on charge collection, particularly in pixelated detector designs and thick sensors (&gt;1 mm). In this paper, the presence of charge sharing and the magnitude of charge loss were calculated for a 2 mm thick pixelated HF-CdZnTe detector with 250 μm pixel pitch and 25 μm pixel gaps, bonded to the STFC HEXITEC ASIC. Results are compared with a CdTe detector as a reference point and supported with simulations from a Monte-Carlo detector model. Charge sharing events showed minimal charge loss in the HF-CdZnTe, resulting in a spectral resolution of 1.63 ± 0.08 keV Full Width at Half Maximum (FWHM) for bipixel charge sharing events at 59.5 keV. Depth of interaction effects were shown to influence charge loss in shared events. The performance is discussed in relation to the improved hole transport of HF-CdZnTe and comparison with simulated results provided evidence of a uniform electric field

Smoking and smoking cessation in pregnancy. Synthesis of a systematic review

International audienceObjectives: To provide up-to-date evidence-based guidelines for the management of smoking cessation during pregnancy and the post-partum period.Study design: A systematic review of the international literature was undertaken between January 2003 and April 2019. MEDLINE, EMBASE databases and the Cochrane library were searched for a range of predefined key words. All relevant reports in English and French were classified according to their level of evidence ranging from 1(highest) to 4(lowest). The strength of each recommendation was classified according to the Haute Autorité de Santé (French National Authority for Health) ranging from A (highest) to C (lowest).Results: \&quot;Counselling\&quot;, including all types of non-pharmacological interventions, has a moderate benefit on smoking cessation, birth weight and prematurity. The systematic use of measuring expired air CO concentration does not influence smoking abstinence, however, it may be useful in assessing smoked tobacco exposure prior to and after quitting. The use of self-help therapies and health education are recommended in helping pregnant smokers quit and should be advised by healthcare professionals. Nicotine replacement therapies (NRT) may be prescribed to pregnant women who have failed to stop smoking after trying non-pharmacological interventions. Different modes of delivery and dosages can be used in optimizing their efficacy. Smoking in the postpartum period is essential to consider. The same treatment options as during pregnancy can be used.Conclusion: Smoking during pregnancy concerns more than a hundred thousand women each year in France resulting in a major public health burden. Healthcare professionals should be mobilised to employ a range of methods to reduce or even eradicate it

Measurement of the Mass of the Z-Boson and the Energy Calibration of Lep

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