Radiation length measurements with high-resolution telescopes

The radiation length imaging method presented in this work can be used to conduct spatially resolved measurements of scattering angles of particles traversing a object under study. For the measurements a planar object is centred in a high-resolution telescope and the whole setup is positioned in a multi-GeV particle beam. The scattering angle distributions depend on the radiation length $X/X$$_{0}$ of the traversed object. Combining the radiation length information with the reconstructed intersections provides the opportunity to generate 2D images of the measurement objects material profile. Measured radiation length images of detector planes can be compared to existing detector models for validation and, when necessary, improvement of the detector simulation. In order to demonstrate the capabilities and scope of the X/X0 imaging method, several beam tests have been conducted in the last years. The imaged objects varied from a ultra thin vertex detector ladder designed for the Belle II experiment to a prototype module for the ATLAS ITk upgrade. Additionally a series of measurements were conducted to determine the radiation length constant X$_{0}$ of hardened conductive glues. To test systematic effects, such as energy loss due to bremsstrahlung, measurements on copper and aluminium wedges with a continuously increasing radiation length were conducted

Radiation length measurements with high-resolution telescopes

The radiation length imaging method presented in this work can be used to conduct spatially resolved measurements of scattering angles of particles traversing a object under study. For the measurements a planar object is centred in a high-resolution telescope and the whole setup is positioned in a multi-GeV particle beam. The scattering angle distributions depend on the radiation length $X/X$$_{0}$ of the traversed object. Combining the radiation length information with the reconstructed intersections provides the opportunity to generate 2D images of the measurement objects material profile. Measured radiation length images of detector planes can be compared to existing detector models for validation and, when necessary, improvement of the detector simulation. In order to demonstrate the capabilities and scope of the X/X0 imaging method, several beam tests have been conducted in the last years. The imaged objects varied from a ultra thin vertex detector ladder designed for the Belle II experiment to a prototype module for the ATLAS ITk upgrade. Additionally a series of measurements were conducted to determine the radiation length constant X$_{0}$ of hardened conductive glues. To test systematic effects, such as energy loss due to bremsstrahlung, measurements on copper and aluminium wedges with a continuously increasing radiation length were conducted

Mapping the material distribution of a complex structure in an electron beam

The simulation and analysis of High Energy Physics experiments require a realisticsimulation of the detector material and its distribution. The challenge is to describe all activeand passive parts of large scale detectors like ATLAS in terms of their size, position and materialcomposition. The common method for estimating the radiation length by weighing individualcomponents, adding up their contributions and averaging the resulting material distribution overextended structures provides a good general estimate, but can deviate significantly from the materialactually present.A method has been developed to assess its material distribution with high spatial resolutionusing the reconstructed scattering angles and hit positions of high energy electron tracks traversingan object under investigation. The study presented here shows measurements for an extendedstructure with a highly inhomogeneous material distribution. The structure under investigation isan End-of-Substructure-card prototype designed for the ATLAS Inner Tracker strip tracker — aPCB populated with components of a large range of material budgets and sizes.The measurements presented here summarise requirements for data samples and reconstructedelectron tracks for reliable image reconstruction of large scale, inhomogeneous samples, choicesof pixel sizes compared to the size of features under investigation as well as a bremsstrahlungcorrection for high material densities and thicknesses

Worst-Case X-ray Photon Energies in Ultrashort Pulse Laser Processing

Ultrashort pulse laser processing can result in the secondary generation of unwanted X-rays if a critical laser irradiance of about 1013 W cm−2 is exceeded. Spectral X-ray emissions were investigated during the processing of tungsten and steel using three complementary spectrometers (based on CdTe and silicon drift detectors) simultaneously for the identification of a worst-case spectral scenario. Therefore, maximum X-ray photon energies were determined, and corresponding dose equivalent rates were calculated. An ultrashort pulse laser workstation with a pulse duration of 274 fs, a center wavelength of 1030 nm, pulse repetition rates between 50 kHz and 200 kHz, and a Gaussian laser beam focused to a spot diameter of 33 μm was employed in a single pulse and burst laser operation mode. Different combinations of laser pulse energy and repetition rate were utilized, keeping the average laser power constant close to the maximum power of 20 W. Peak irradiances I0 ranging from 7.3 × 1013 W cm−2 up to 3.0 × 1014 W cm−2 were used. The X-ray dose equivalent rate increases for lower repetition rates and higher pulse energy if a constant average power is used. Laser processing with burst mode significantly increases the dose rates and the X-ray photon energies. A maximum X-ray photon energy of about 40 keV was observed for burst mode processing of tungsten with a repetition rate of 50 kHz and a peak irradiance of 3 × 1014 W cm−2

X-ray Emission Hazards from Ultrashort Pulsed Laser Material Processing in an Industrial Setting

Interactions between ultrashort laser pulses with intensities larger than 1013 W/cm2 and solids during material processing can lead to the emission of X-rays with photon energies above 5 keV, causing radiation hazards to operators. A framework for inspecting X-ray emission hazards during laser material processing has yet to be developed. One requirement for conducting radiation protection inspections is using a reference scenario, i.e., laser settings and process parameters that will lead to an almost constant and high level of X-ray emissions. To study the feasibility of setting up a reference scenario in practice, ambient dose rates and photon energies were measured using traceable measurement equipment in an industrial setting at SCHOTT AG. Ultrashort pulsed (USP) lasers with a maximum average power of 220 W provided the opportunity to measure X-ray emissions at laser peak intensities of up to 3.3 × 1015 W/cm2 at pulse durations of ~1 ps. The results indicate that increasing the laser peak intensity is insufficient to generate high dose rates. The investigations were affected by various constraints which prevented measuring high ambient dose rates. In this work, a list of issues which may be encountered when performing measurements at USP-laser machines in industrial settings is identified

EUDAQ—a data acquisition software framework for common beam telescopes

EUDAQ is a generic data acquisition software developed for use in conjunction with common beam telescopes at charged particle beam lines. Providing high-precision reference tracks for performance studies of new sensors, beam telescopes are essential for the research and development towards future detectors for high-energy physics. As beam time is a highly limited resource, EUDAQ has been designed with reliability and ease-of-use in mind. It enables flexible integration of different independent devices under test via their specific data acquisition systems into a top-level framework. EUDAQ controls all components globally, handles the data flow centrally and synchronises and records the data streams. Over the past decade, EUDAQ has been deployed as part of a wide range of successful test beam campaigns and detector development applications

The association between genetically elevated polyunsaturated fatty acids and risk of cancer

Auteurs : Fatty Acids in Cancer Mendelian Randomization CollaborationInternational audienceBackground: The causal relevance of polyunsaturated fatty acids (PUFAs) for risk of site-specific cancers remains uncertain. Methods: Using a Mendelian randomization (MR) framework, we assessed the causal relevance of PUFAs for risk of cancer in European and East Asian ancestry individuals. We defined the primary exposure as PUFA desaturase activity, proxied by rs174546 at the FADS locus. Secondary exposures were defined as omega 3 and omega 6 PUFAs that could be proxied by genetic polymorphisms outside the FADS region. Our study used summary genetic data on 10 PUFAs and 67 cancers, corresponding to 562,871 cases and 1,619,465 controls, collected by the Fatty Acids in Cancer Mendelian Randomization Collaboration. We estimated odds ratios (ORs) for cancer per standard deviation increase in genetically proxied PUFA exposures. Findings: Genetically elevated PUFA desaturase activity was associated (P < 0.0007) with higher risk (OR [95% confidence interval]) of colorectal cancer (1.09 [1.07–1.11]), esophageal squamous cell carcinoma (1.16 [1.06–1.26]), lung cancer (1.06 [1.03–1.08]) and basal cell carcinoma (1.05 [1.02–1.07]). There was little evidence for associations with reproductive cancers (OR = 1.00 [95% CI: 0.99–1.01]; Pheterogeneity = 0.25), urinary system cancers (1.03 [0.99–1.06], Pheterogeneity = 0.51), nervous system cancers (0.99 [0.95–1.03], Pheterogeneity = 0.92) or blood cancers (1.01 [0.98–1.04], Pheterogeneity = 0.09). Findings for colorectal cancer and esophageal squamous cell carcinoma remained compatible with causality in sensitivity analyses for violations of assumptions. Secondary MR analyses highlighted higher omega 6 PUFAs (arachidonic acid, gamma-linolenic acid and dihomo-gamma-linolenic acid) as potential mediators. PUFA biosynthesis is known to interact with aspirin, which increases risk of bleeding and inflammatory bowel disease. In a phenome-wide MR study of non-neoplastic diseases, we found that genetic lowering of PUFA desaturase activity, mimicking a hypothetical intervention to reduce cancer risk, was associated (P < 0.0006) with increased risk of inflammatory bowel disease but not bleeding. Interpretation: The PUFA biosynthesis pathway may be an intervention target for prevention of colorectal cancer and esophageal squamous cell carcinoma but with potential for increased risk of inflammatory bowel disease. Funding: Cancer Resesrch UK (C52724/A20138, C18281/A19169). UK Medical Research Council (MR/P014054/1). National Institute for Health Research (NIHR202411). UK Medical Research Council (MC_UU_00011/1, MC_UU_00011/3, MC_UU_00011/6, and MC_UU_00011/4). National Cancer Institute (R00 CA215360). National Institutes of Health ( U01 CA164973, R01 CA60987, R01 CA72520, U01 CA74806, R01 CA55874, U01 CA164973 and U01 CA164973)

Data quality monitors of vertex detectors at the start of the Belle II experiment

The Belle II experiment features a substantial upgrade of the Belle detector and will operate at the SuperKEKB energy-asymmetric e+e− collider at KEK in Tsukuba, Japan. The accelerator completed its first phase of commissioning in 2016, and the Belle II detector saw its first electron-positron collisions in April 2018. Belle II features a newly designed silicon vertex detector based on double-sided strip layers and DEPFET pixel layers. A subset of the vertex detector was operated in 2018 to determine background conditions (Phase 2 operation). The collaboration completed full detector installation in January 2019, and the experiment started full data taking. This paper will report on the final arrangement of the silicon vertex detector part of Belle II with a focus on online monitoring of detector conditions and data quality, on the design and use of diagnostic and reference plots, and on integration with the software framework of Belle II. Data quality monitoring plots will be discussed with a focus on simulation and acquired cosmic and collision data