Practical all-to-all propagators for lattice QCD

A new method for computing all elements of the lattice quark propagator is proposed. The method combines the spectral decomposition of the propagator, computing the lowest eigenmodes exactly, with noisy estimators which are ‘diluted’, i.e. taken to have support only on a subset of time, space, spin or color. We find that the errors are dramatically reduced compared to traditional noisy estimator techniques.     

The fraction of ischaemic heart disease and stroke attributable to smoking in the WHO Western Pacific and South-East Asian regions

Background

Tobacco will soon be the biggest cause of death worldwide, with the greatest burden being borne by low and middle‐income countries where 8/10 smokers now live.

Objective

This study aimed to quantify the direct burden of smoking for cardiovascular diseases (CVD) by calculating the population attributable fractions (PAF) for fatal ischaemic heart disease (IHD) and stroke (haemorrhagic and ischaemic) for all 38 countries in the World Health Organization Western Pacific and South East Asian regions.

Design and subjects

Sex‐specific prevalence of smoking was obtained from existing data. Estimates of the hazard ratio (HR) for IHD and stroke with smoking as an independent risk factor were obtained from the ∼600 000 adult subjects in the Asia Pacific Cohort Studies Collaboration (APCSC). HR estimates and prevalence were then used to calculate sex‐specific PAF for IHD and stroke by country.

Results

The prevalence of smoking in the 33 countries, for which relevant data could be obtained, ranged from 28–82% in males and from 1–65% in females. The fraction of IHD attributable to smoking ranged from 13–33% in males and from <1–28% in females. The percentage of haemorrhagic stroke attributable to smoking ranged from 4–12% in males and from <1–9% in females. Corresponding figures for ischaemic stroke were 11–27% in males and <1–22% in females.

Conclusions

Up to 30% of some cardiovascular fatalities can be attributed to smoking. This is likely an underestimate of the current burden of smoking on CVD, given that the smoking epidemic has developed further since many of the studies were conducted.     

Fast analytical methods for the correction of signal random time-shifts and application to segmented HPGe detectors

Detection systems rely more and more on on-line or off-line comparison of detected signals with basis signals in order to determine the characteristics of the impinging particles. Unfortunately, these comparisons are very sensitive to the random time-shifts that may alter the signal delivered by the detectors. We present two fast algebraic methods to determine the value of the time-shift and to enhance the reliability of the comparison to the basis signals.     

Search for ultra-high energy photons with the Pierre Auger Observatory

The Pierre Auger Observatory [1] has an unprecedented sensitivity to photons at energies above 10¹⁸ eV. Particularly the combination of ground array and fluorescence detection techniques offers a unique power to discriminate the primary particles based on different observables. Implications of photon searches extend from astrophysics to fundamental and particle physics. Current results and future prospects are reported.     

HPGe detectors for low-temperature nuclear orientation

Using the Low-Temperature Nuclear Orientation (LTNO) technique one can study various interesting properties of atomic nuclei and nuclear decay which can be deduced from the measurements of the angular distributions of charged particles emitted during the decay. However, the use of particle detectors working in conditions of LTNO devices (which are generally not available commercially) is a necessary precondition for the realization of these experiments.

Planar HPGe detectors for detection of charged particles at “liquid helium” temperatures were developed and produced at NPI e . Relatively simple technology using vacuum evaporation and diffusion was employed. The performance of detectors at low temperatures was tested and their characteristics measured in a testing cryostat before using them in real experiments.

The HPGe detectors were extensively used in a whole range of LTNO experiments with various physical objectives — in offline (IKS Leuven) as well as online (CERN-ISOLDE, Louvain-la-Neuve — LISOL) experiments. In frame of the project “Meson-Exchange Enhancement of First-Forbidden Beta Transitions in the Lead Region”, the measurements of angular distribution of emitted β-particles allowed to determine experimentally the “meson-exchange currents” contribution to the β-decay. In the project “Isospin Mixing in NZ nuclei”, the isospin-forbidden β-transitions of the nuclei in region (A=50–100) were studied in order to obtain information on the isospin structure of the nuclear states. A new project looking for the possible presence of the tensor currents contribution to the β-decay is being prepared for the CERN-ISOLDE facility.     

Atmospheric monitoring and its impact on air shower observables at the Pierre Auger Observatory

The Pierre Auger Observatory, completed in September 2008, detects cosmic rays by observing and studying the development of extensive air showers in atmosphere. The atmosphere itself, with its unpredictable changes of conditions, directly influences the estimation of the air shower characteristics. In this paper, all the instruments and techniques adopted by the Auger Observatory are explained, and the impact of their results on the most important shower parameters are shown.     

Monte Carlo errors with less errors

We explain in detail how to estimate mean values and assess statistical errors for arbitrary functions of elementary observables in Monte Carlo simulations. The method is to estimate and sum the relevant autocorrelation functions, which is argued to produce more certain error estimates than binning techniques and hence to help toward a better exploitation of expensive simulations. An effective integrated autocorrelation time is computed which is suitable to benchmark efficiencies of simulation algorithms with regard to specific observables of interest. A Matlab code is offered for download that implements the method. It can also combine independent runs (replica) allowing to judge their consistency.     

The performance of the AMS-02 silicon tracker evaluated during the pre-integration phase of the spectrometer

The Alpha Magnetic Spectrometer is a large acceptance cosmic-ray detector (0.5 m² sr) designed to operate at an altitude of 400 km on the International Space Station. The AMS-02 silicon tracker contains 2264 silicon microstrip sensors (total active area 6.75 m²). The internal alignment parameters of the assembled tracker have been determined on the ground with cosmic-ray muons. The results for the alignment precision and position resolution are reported.     

KM3NeT: Present status and potentiality for the search for exotic particles

The aim of the KM3NeT Project is to build a very large volume (more than 1 km³) neutrino telescope in the Mediterranean Sea. The up to date status of the project is presented, and the main physics goals are reviewed. The possibility to search for super-massive exotic particles (magnetic monopoles, nuclearites, Q-balls) is addressed in the final part of the paper.