EPICS Based Control System for SPES Tape Station for Beam Characterization: Motion System and Controls

International audienceThe SPES* Tape Station (STS) for Radioactive Ion Beams (RIBs) characterization is under construction at LNL. This tool will be used to measure the actual composition of the radioactive ion beams extracted from the SPES-β ion source and to optimize the source’s parameters. STS will provide beam diagnostic information by determining the beam composition and intensity. At the same time, it will be able to measure the target release curves needed for the source’s characterization and development. The core part of the system, the related motor and controls are being designed and constructed in synergy with IPN Orsay (France), iThemba Laboratories (South Africa) and the Gamma collaboration (INFN-CSN3). In particular, the mechanical part is based on the existing BEDO** tape system operated in ALTO while the control system for motion is an EPICS*** base application under implementation by iThemba and INFN, result of a upgrade operation required to substitute obsoleted hardware and update logic and algorithm

Dip-coated screen for gain calibration and alignment of gamma-ray telescope mirrors

In this communication, we will present a dual-purpose calibration system of NectarCAM, a medium-size-telescope camera proposed for the Cherenkov Telescope Array (CTA). The device is based on a white diffuse-reflective screen mounted on an XY motorization to reach every location in the focal plane, including a parking position when not in use. The design of the system was led by the requirements to perform the mirror alignment and the study of the telescope Point Spread Function (PSF) on one side (A), and to calibrate the photodetection chains (one for each of the 1855 photomultiplier tubes) of the camera in single photoelectron mode on the other side (B). The main requirement for the calibration device consists in producing a high-reflective (> 90% between 450 nm and 700 nm) and diffusive (following Lambert's cosine law) surface for side A. The other side, B, should emit an homogeneous amount of light over the surface. To satisfy these requirements, we developed a unique screen made out of PMMA and coated with the BC-620 paint from Saint-Gobain. For single-photoelectron calibration purposes, light is produced by a pulsed light source and injected into the screen via a fishtail light guide. We studied the optimal screen shape, paint, and painting process. To do so, we produced several prototypes and compared the light output intensity over the screen surface. These studies led to the definition of a specific painting pattern that enhances the light emission uniformity over the final octagonal screen surface. After having briefly described the developed prototypes that led to the current calibration device, we will focus on the calibration system performances and will describe the dip-coating application process, which is an essential technique to achieve reliable and reproducible optical performances

Design and characterization of a single photoelectron calibration system for the NectarCAM camera of the medium-sized telescopes of the Cherenkov Telescope Array

International audienceIn this work, we describe the optical properties of the single photoelectron (SPE) calibration system designed for NectarCAM, a camera proposed for the Medium Sized Telescopes (MST) of the Cherenkov Telescope Array (CTA). One of the goals of the SPE system, as integral part of the NectarCAM camera, consists in measuring with high accuracy the gain of its photo-detection chain. The SPE system is based on a white painted screen where light pulses are injected through a fishtail light guide from a dedicated flasher. The screen – placed 15 mm away from the focal plane – is mounted on an XY motorization that allows movements over all the camera plane. This allows in-situ measurements of the SPE spectra via a complete scan of the 1855 photo-multiplier tubes (PMTs) of NectarCAM. This calibration process will enable the reduction of the systematic uncertainties on the energy reconstruction of γ -rays coming from distant astronomical sources and detected by CTA.We discuss the design of the screen used in the calibration system and we present its optical performances in terms of light homogeneity and timing of the signal

Dip-coated screen for gain calibration and alignment of gamma-ray telescope mirrors

In this communication, we will present a dual-purpose calibration system of NectarCAM, a medium-size-telescope camera proposed for the Cherenkov Telescope Array (CTA). The device is based on a white diffuse-reflective screen mounted on an XY motorization to reach every location in the focal plane, including a parking position when not in use. The design of the system was led by the requirements to perform the mirror alignment and the study of the telescope Point Spread Function (PSF) on one side (A), and to calibrate the photodetection chains (one for each of the 1855 photomultiplier tubes) of the camera in single photoelectron mode on the other side (B). The main requirement for the calibration device consists in producing a high-reflective (> 90% between 450 nm and 700 nm) and diffusive (following Lambert's cosine law) surface for side A. The other side, B, should emit an homogeneous amount of light over the surface. To satisfy these requirements, we developed a unique screen made out of PMMA and coated with the BC-620 paint from Saint-Gobain. For single-photoelectron calibration purposes, light is produced by a pulsed light source and injected into the screen via a fishtail light guide. We studied the optimal screen shape, paint, and painting process. To do so, we produced several prototypes and compared the light output intensity over the screen surface. These studies led to the definition of a specific painting pattern that enhances the light emission uniformity over the final octagonal screen surface. After having briefly described the developed prototypes that led to the current calibration device, we will focus on the calibration system performances and will describe the dip-coating application process, which is an essential technique to achieve reliable and reproducible optical performances

Dip-coated screen for gain calibration and alignment of gamma-ray telescope mirrors

In this communication, we will present a dual-purpose calibration system of NectarCAM, a medium-size-telescope camera proposed for the Cherenkov Telescope Array (CTA). The device is based on a white diffuse-reflective screen mounted on an XY motorization to reach every location in the focal plane, including a parking position when not in use. The design of the system was led by the requirements to perform the mirror alignment and the study of the telescope Point Spread Function (PSF) on one side (A), and to calibrate the photodetection chains (one for each of the 1855 photomultiplier tubes) of the camera in single photoelectron mode on the other side (B). The main requirement for the calibration device consists in producing a high-reflective (> 90% between 450 nm and 700 nm) and diffusive (following Lambert's cosine law) surface for side A. The other side, B, should emit an homogeneous amount of light over the surface. To satisfy these requirements, we developed a unique screen made out of PMMA and coated with the BC-620 paint from Saint-Gobain. For single-photoelectron calibration purposes, light is produced by a pulsed light source and injected into the screen via a fishtail light guide. We studied the optimal screen shape, paint, and painting process. To do so, we produced several prototypes and compared the light output intensity over the screen surface. These studies led to the definition of a specific painting pattern that enhances the light emission uniformity over the final octagonal screen surface. After having briefly described the developed prototypes that led to the current calibration device, we will focus on the calibration system performances and will describe the dip-coating application process, which is an essential technique to achieve reliable and reproducible optical performances

Dip-coated screen for gain calibration and alignment of gamma-ray telescope mirrors

In this communication, we will present a dual-purpose calibration system of NectarCAM, a medium-size-telescope camera proposed for the Cherenkov Telescope Array (CTA). The device is based on a white diffuse-reflective screen mounted on an XY motorization to reach every location in the focal plane, including a parking position when not in use. The design of the system was led by the requirements to perform the mirror alignment and the study of the telescope Point Spread Function (PSF) on one side (A), and to calibrate the photodetection chains (one for each of the 1855 photomultiplier tubes) of the camera in single photoelectron mode on the other side (B). The main requirement for the calibration device consists in producing a high-reflective (> 90% between 450 nm and 700 nm) and diffusive (following Lambert's cosine law) surface for side A. The other side, B, should emit an homogeneous amount of light over the surface. To satisfy these requirements, we developed a unique screen made out of PMMA and coated with the BC-620 paint from Saint-Gobain. For single-photoelectron calibration purposes, light is produced by a pulsed light source and injected into the screen via a fishtail light guide. We studied the optimal screen shape, paint, and painting process. To do so, we produced several prototypes and compared the light output intensity over the screen surface. These studies led to the definition of a specific painting pattern that enhances the light emission uniformity over the final octagonal screen surface. After having briefly described the developed prototypes that led to the current calibration device, we will focus on the calibration system performances and will describe the dip-coating application process, which is an essential technique to achieve reliable and reproducible optical performances

Dip-coated screen for gain calibration and alignment of gamma-ray telescope mirrors

International audienceIn this communication, we will present a dual-purpose calibration system of NectarCAM, a medium-size-telescope camera proposed for the Cherenkov Telescope Array (CTA). The device is based on a white diffuse-reflective screen mounted on an XY motorization to reach every location in the focal plane, including a parking position when not in use. The design of the system was led by the requirements to perform the mirror alignment and the study of the telescope Point Spread Function (PSF) on one side (A), and to calibrate the photodetection chains (one for each of the 1855 photomultiplier tubes) of the camera in single photoelectron mode on the other side (B). The main requirement for the calibration device consists in producing a high-reflective (> 90% between 450 nm and 700 nm) and diffusive (following Lambert's cosine law) surface for side A. The other side, B, should emit an homogeneous amount of light over the surface. To satisfy these requirements, we developed a unique screen made out of PMMA and coated with the BC-620 paint from Saint-Gobain. For single-photoelectron calibration purposes, light is produced by a pulsed light source and injected into the screen via a fishtail light guide. We studied the optimal screen shape, paint, and painting process. To do so, we produced several prototypes and compared the light output intensity over the screen surface. These studies led to the definition of a specific painting pattern that enhances the light emission uniformity over the final octagonal screen surface. After having briefly described the developed prototypes that led to the current calibration device, we will focus on the calibration system performances and will describe the dip-coating application process, which is an essential technique to achieve reliable and reproducible optical performances