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Workshop MPGD Applications Beyond Fundamental Science (from 15th-16th September)
From their beginning, MPGDs have played a fundamental role in HEP and Nuclear Physics. Today, due to the mature development stage of MPGDs, their applications are being extended beyond fundamental Science. The workshop on MPGD Applications Beyond Fundamental Science, intends to gather scientists and developments of applications in the fields of (but not limited to):
We are looking forward to see you in Aveiro and sharing your work with whole the MPGD community:
Leszek, Silvia, João and Carlos
We are developing a new detector concept for simultaneous imaging and spectroscopy of fast neutrons and gammas; it combines a liquid-Xe (LXe) scintillator coupled to a UV-sensitive gaseous imaging photomultiplier (GPM).
The research focuses on validating this new idea for simultaneously detecting concealed explosives, comprising low-Z materials, and high-Z fissile materials, utilizing respectively fast-neutron resonant transmission radiography and dual discrete gamma-ray radiography. Neutron spectroscopy is performed by Time-Of-Flight; gamma-ray analysis requires pulse-height analysis. Imaging of both relies on scintillation-light localization from a liquid xenon (LXe) converter, with a UV-
sensitive, cascaded-THGEM/CsI gaseous photomultiplier (GPM).
The properties of an imaging-GPM, in Ne/CH 4 mixtures at cryogenic temperatures, will be presented. Localization properties will be given for low-energy gammas and fast neutrons, using pad readout electronics, in combination with LXe-filled capillary neutron and gamma-ray converter. The experimental results, obtained with gamma-ray and fast-neutron sources will be compared with that of extended GEANT-4 simulations.
In recent years, MPGDs found applications beyond High Energy Physics mainly due to their imaging capabilities. Typically, MPGDs have the signals read out electronically, this means that each channel has its own amplification and digitisation chain. Despite being unavoidable in some occasions, an alternative to this approach exists: the so-called optical readout. Scintillation light produced during the amplification avalanche can be detected, making the gaseous detector a scintillating plate with extraordinary light yield. The first ideas of taking pictures of scintillating gases go back to the beginning of the ’80. For instance, Charpak and collaborators used an image intensifier camera to photograph a parallel plate avalanche detector filled with Ar/CH4/TEA. The choice of the gas mixture was mainly driven by the scintillation spectrum. Unfortunately, not many gases scintillate in the visible window, for which most of the light sensors are optimised. CF4 is one of them, and the mixture of Ar/CF4 80/20 emits orange light in a broad peak around 630 nm. Modern MPGDs coupled with modern cameras are very promising tools to deliver fast and good quality images: This robust and versatile device is ideal for imaging purposes and can find several applications, for instance x-ray radiography and fluoroscopy, energy-resolved photon counting, and x-ray crystallography. The focus of the talk will be put on the recent developments of the optical readout for MPGDs at CERN.
Three muon telescopes based on multiplexed Micromegas have recently been built for the ScanPyramids mission whose aim is to image four Egyptian pyramids in Giza and Daschour sites. These telescopes were installed early June on the North and East faces of Khufu and took data during 2-3 months. We will report in this talk on their operation in extreme conditions (temperature, dust in particular) and their general performance.
Imaging applications with Gas Electron Multipliers as amplification devices provide excellent spatial resolution (of the order of hundreds of μm) for areas as large as 10x10 cm2, making use of discrete channel readout. A drawback is the need for complex and expensive electronic systems. In applications where resolutions of the order of the mm are required, a simpler and cheaper solution is to determine the position of the interaction using the resistive charge division method. This solution requires a minimum of 4 readout channels to achieve 2D imaging over large areas, greatly simplifying the electronic system. A large signal-to-noise ratio is however required with the GEM’s operating at high gain, in some cases, near the discharge limit.
We have developed a non-standard GEM, made from a 100 micron thick kapton foil (2-fold thicker than standard GEM’s). The 100 micron thick GEM is produced using the same wet etching technique as the standard GEM and is virtually immune to discharges. A robust detector that can safely operate at the high gains necessary to achieve an adequate signal-to-noise ratio for imaging applications was developed.
In this work we present the results obtained with a detector composed by two 100 micron thick GEM and a 10x10 cm2 2D readout electrode with resistive lines. Energy resolution of 21% and charge gains above 104 have been measured, with a 55Fe radioactive source. Results of the detector characterization for imaging applications are also presented.
We present imaging results of needle-like and planar 22Na sources obtained with a prototype of a high-acceptance small-animal positron emission tomograph based on patterned resistive plate chambers (RPC-PET). The maximum-likelihood expectation-maximization (MLEM) reconstruction of the acquired data yielded an excellent and stable resolution of 0.4 mm FWHM.
Remarkable scientific and technological progress during the last years has led to the construction of accelerator based facilities dedicated to hadron therapy. This kind of technology requires precise and continuous control of position, intensity and shape of the ions or protons used to irradiate cancers. Patient safety, accelerator operation and dose delivery should be optimized by a real time monitoring of beam intensity and profile before and during the treatment, by using non-destructive, high spatial resolution detectors. For this purpose, inspired by a prototype designed and developed at LNF as beam detector monitor for the DAFNE e+e- machine, the authors have studied and built a beam monitor for hadron therapy application. Based on Micro Pattern Gaseous Detectors (MPGDs), it is called TPC-GEM (TPG) detector and is characterized by high spatial resolution and rate capability. Due to the low amount of material in the active volume, it is “not invasive”, therefore the beam characteristics are preserved, so minimizing the uncertainties on beam position, intensity, energy and stability.
Deriving from nuclear weapons tests and the nuclear power plant accidents, 137Cs is present in almost all soils in Europe, due to its relatively long half-life of 30.2 years, and it is the main source of artificial γ-radiation. As a consequence of Chernobyl accident in 1986, most European countries extended their γ-dose rate monitoring networks for early warning, moreover the Fukushima disaster in 2011 triggered the need for a series of further improvements for radiation protection. The types of detector in use for these monitoring networks are Geiger-Müller counters, proportional counters, scintillation detectors and ionization chambers. With the aim to design a new gamma detector characterized by higher sensitivity and efficiency, larger active volume and low costs, the authors are studying a potential use of MPGDs for environmental gamma measurements.
The aim of this talk is to present two applications of MPGDs beyond HEP under study: quality assurance in cancer treatments and radiological monitoring. The Monte Carlo simulations of the beam monitor prototype carried out to optimize the geometrical set up and to predict the detector behavior will be shown. The experimental results of the TPC-GEM characterization using an X-ray tube will be presented, as well as the future developments. Moreover the preliminary feasibility study for environmental gamma rays detection based on Monte Carlo simulations will also be shown.