Modern detector science and technology has originated from High Energy Physics experiment needs in the '80's of the past century, based on the achievement and knowledge of the silicon industry of the ...time. The first segmented array of diodes (a microstrip sensor) was developed to track vertices at the NA11 experiment at the SPS accelerator at CERN (Geneva, CH) . During the following years, detector technology developed into a special branch of the huge silicon technology enterprise that has been arguably the biggest contributor to the evolution of most of the economical, social and scientific activities of mankind. If, and how, detector technology for science has kept the pace with the spectacular speed of evolution of mainstream silicon technology (namely, the microelectronics industry) is the object of this paper, that will also point out the special requirements of detectors for science and how these can be linked to modern microelectronics trends.
Recent developments on silicon detectors Casse, G.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2013, Letnik:
732
Journal Article
Recenzirano
Silicon detectors have risen to a predominant role in high energy physics experiments since their introduction just over thirty years ago. Their outstanding capabilities of high resolution, low mass ...and fast response to ionising radiation have given silicon detectors the role of device of choice for the inner regions of collider experiments. Their evolution over the years has been notable, and it is possibly accelerating in the present times with the impulse coming from stringent requirements of future experiments and from developments in the microelectronics industry. Recent advancements of silicon detectors are reviewed and reported from the perspective of future challenges.
The most likely path formalism (MLP) is widely established as the most statistically precise method for proton path reconstruction in proton computed tomography. However, while this method accounts ...for small-angle multiple coulomb scattering (MCS) and energy loss, inelastic nuclear interactions play an influential role in a significant number of proton paths. By applying cuts based on energy and direction, tracks influenced by nuclear interactions are largely discarded from the MLP analysis. In this work we propose a new method to estimate the proton paths based on a deep neural network (DNN). Through this approach, estimates of proton paths equivalent to MLP predictions have been achieved in the case where only MCS occurs, together with an increased accuracy when nuclear interactions are present. Moreover, our tests indicate that the DNN algorithm can be considerably faster than the MLP algorithm.
Abstract
Silicon sensors are the most diffuse position sensitive
device in particle physics experiments and in countless applications
in science and technology. They had a spectacular progress in
...performance over almost 40 years since their first introduction, but
their evolution is now slowing down. The position resolution for
single particle hits is larger than a few microns in the most
advanced sensors. This value was reached already over 30 years
ago 1. The minimum ionising path length a sensor can detect
is several tens of microns. There are fundamental reasons why these
limits will not be substantially improved by further refinements of
the current technology. This makes silicon sensors unsuitable to
applications where the physics signature is the short path of a
recoiling atom and constrains the layout of physics experiments
where they represent by far the best option like high energy physics
collider experiments. In perspective, the availability of sensors
with sub-micron spatial resolution, in the order of a few tens of
nanometres, would be a disruptive change for the sensor technology
with a foreseeable huge impact on experiment layout and various
applications of these devices. For providing such a leap in
resolution, we propose a novel design based on a purely digital
circuit. This disruptive concept potentially enables pixel sizes
much smaller than 1 μm
2
and a number of advantages in
terms of power consumption, readout speed and reduced thickness (for
low mass sensors).
The ATLAS upgrade Planar Pixel Sensors (PPS) project aims to prove the suitability of silicon detectors processed with planar technology to equip all layers of the pixel vertex detector proposed for ...the upgrade of the ATLAS experiment for the future High Luminosity LHC at CERN (HL-LHC). The detectors need to be radiation tolerant to the extreme fluences expected to be received during the experimental lifetime, with optimised geometry for full coverage and high granularity and affordable in term of cost, due to the relatively large area of the upgraded ATLAS detector system. Here several solutions for the detector geometry and results with radiation hard technologies (n-in-n, n-in-p) are discussed.
The reverse current of irradiated silicon sensors leads to self heating of the sensor and degrades the signal to noise ratio of a detector. Precise knowledge of the expected reverse current during ...detector operation is crucial for planning and running experiments in High Energy Physics. The dependence of the reverse current on sensor temperature and irradiation fluence is parametrized by the effective energy and the current related damage rate, respectively. In this study 18 n-in-p mini silicon strip sensors from companies Hamamatsu Photonics and Micron Semiconductor Ltd. were deployed. Measurements of the reverse current for different bias voltages were performed at temperatures of −32°C, −27°C and −23°C. The sensors were irradiated with reactor neutrons in Ljubljana to fluences ranging from 2×1014neq∕cm2 to 2×1016neq∕cm2. The measurements were performed directly after irradiation and after 10 and 30 days of room temperature annealing. The aim of the study presented in this paper is to investigate the reverse current of silicon sensors for high fluences of up to 2×1016neq∕cm2 and compare the measurements to the parametrization models.
Purpose:
Radiography and tomography using proton beams promise benefit to image guidance and treatment planning for proton therapy. A novel proton tracking detector is described and experimental ...demonstrations at a therapy facility are reported. A new type of proton CT reconstructing relative “scattering power” rather than “stopping power” is also demonstrated. Notably, this new type of imaging does not require the measurement of the residual energies of the protons.
Methods:
A large area, silicon microstrip tracker with high spatial and temporal resolution has been developed by the Proton Radiotherapy Verification and Dosimetry Applications consortium and commissioned using beams of protons at iThemba LABS, Medical Radiation Department, South Africa. The tracker comprises twelve planes of silicon developed using technology from high energy physics with each plane having an active area of ∼10 × 10 cm segmented into 2048 microstrips. The tracker is organized into four separate units each containing three detectors at 60° to one another creating an x-u-v coordinate system. Pairs of tracking units are used to reconstruct vertices for protons entering and exiting a phantom containing tissue equivalent inserts. By measuring the position and direction of each proton before and after the phantom, the nonlinear path for each proton through an object can be reconstructed.
Results:
Experimental results are reported for tracking the path of protons with initial energies of 125 and 191 MeV. A spherical phantom of 75 mm diameter was imaged by positioning it between the entrance and exit detectors of the tracker. Positions and directions of individual protons were used to create angular distributions and 2D fluence maps of the beam. These results were acquired for 36 equally spaced projections spanning 180°, allowing, for the first time, an experimental CT image based upon the relative scattering power of protons to be reconstructed.
Conclusions:
Successful tracking of protons through a thick target (phantom) has demonstrated that the tracker discussed in this paper can provide the precise directional information needed to perform proton radiography and tomography. When synchronized with a range telescope, this could enable the reconstruction of proton CT images of stopping power. Furthermore, by measuring the deflection of many protons through a phantom, it was demonstrated that it is possible to reconstruct a new kind of CT image (scattering power) based upon this tracking information alone.
This paper describes a new method for optical readout of Time Projection Chambers (TPCs), based on the Linearly Graded Silicon Photomultiplier (LG-SiPM). This is a single photon-sensitive detector ...with excellent timing and 2D position resolution developed at Fondazione Bruno Kessler, Trento (FBK). The LG-SiPM produces time-varying voltage signals that are used to reconstruct the 3D position and energy of ionisation tracks generated inside the TPC. The TPC used in this work contained room-temperature CF4 gas at a pressure of 100 mbar, with two THGEMs to produce secondary scintillation light. A collimated 241Am source (Qα=5.486 MeV) was used to produce the ionisation tracks. The successful reconstruction of these tracks is demonstrated, and the consistency of the methodology characterised through varying the geometry of the tracks within the TPC. Energy reconstruction and deposition studies are also described, demonstrating the feasibility of the LG-SiPM as a potential option for optical TPC readout.
Abstract
This article details the design of a silicon based polarimeter for use in a prototype storage ring for proton EDM (Electric Dipole Moment) studies. The polarimeter consists of layers of LGAD ...(Low Gain Avalanche Diode) sensors for a low material budget, time-of-flight measurement and complemented with HV-CMOS (High Voltage CMOS) sensors for accurate scattering angle measurement and tracking. This design has the objective to optimize the polarization measurement of protons with energy 30–45 MeV. Simulations show that the excellent time resolution of LGAD sensors provides a sufficient energy resolution to meet the experiment specifications. HV-CMOS sensors are included to provide complementary spatial resolution with minimal additional material budget. The simulations show that the detector configuration is capable of measuring the scattering angle of a proton scattered off a carbon target to just a few hundredths of a degree. The time-of-flight measurement performance is demonstrated with lab experiments using electrons from a Sr90 source.
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