Electric fields, weighting fields, signals and charge diffusion in detectors including resistive materials

In this report we discuss static and time dependent electric fields in detector geometries with an arbitrary number of parallel layers of a given permittivity and weak conductivity. We derive the Green's functions i.e. the field of a point charge, as well as the weighting fields for readout pads and readout strips in these geometries. The effect of 'bulk' resistivity on electric fields and signals is investigated. The spreading of charge on thin resistive layers is also discussed in detail, and the conditions for allowing the effect to be described by the diffusion equation is discussed. We apply the results to derive fields and induced signals in Resistive Plate Chambers, Micromega detectors including resistive layers for charge spreading and discharge protection as well as detectors using resistive charge division readout like the MicroCAT detector. We also discuss in detail how resistive layers affect signal shapes and increase crosstalk between readout electrodes

Particle Physics Instrumentation

This report summarizes a series of three lectures aimed at giving an overview of basic particle detection principles, the interaction of particles with matter, the application of these principles in modern detector systems, as well techniques to read out detector signals in high-rate experiments.Comment: 11 pages, contribution to the 1st Asia-Europe-Pacific School of High-Energy Physics, Fukuoka, Japan, 14 - 27 Oct 201

An application of extensions of the Ramo-Shockley theorem to signals in silicon sensors

We discuss an extension of the Ramo-Shockley theorem that allows the calculation of signals in detectors that contain non-linear materials of arbitrary permittivity and finite conductivity (volume resistivity) as well as a static space-charge. The readout-electrodes can be connected by an arbitrary impedance network. This formulation is useful for the treatment of semiconductor sensors where the finite volume resistivity in the sensitive detector volume cannot be neglected. The signals are calculated by means of time dependent weighting fields and weighting vectors. These are calculated by adding voltage or current signals to the electrodes in question, which has a very practical application when using semiconductor device simulation programs. An analytic example for an un-depleted silicon sensor is given

Passive quenching, signal shapes, and space charge effects in SPADs and SiPMs

In this report we study the dynamics of passive quenching in a single-photon avalanche diode. Our discussion is based on a microscopic description of the electron-hole avalanche coupled to the equivalent circuit of the device, consisting of the quench resistor and the junction capacitance. Analytic expressions for the resulting signal shape are derived from this model for simple electric field configurations, and efficient numerical prescriptions are given for realistic device geometries. Space charge effects are included using simulations. They are shown to distort the signal shape, but alter neither its basic characteristics nor the underlying quenching mechanism

The statistics of electron-hole avalanches

Charge multiplication through avalanche processes is commonly employed in the detection of single photons or charged particles in high-energy physics and beyond. In this report, we provide a detailed discussion of the properties of avalanches driven by two species of charge carriers, e.g. electrons and holes in a semiconductor exposed to an electric field. We derive equations that describe the general case of avalanches developing in inhomogeneous electric fields and give their analytical solutions for constant fields. We discuss consequences for the time resolution achievable with detectors that operate above the breakdown limit, e.g. single-photon avalanche diodes (SPADs) and silicon photomultipliers (SiPMs). Our results also describe avalanches that achieve finite gain and are important for avalanche photodiodes (APDs) and low-gain avalanche detectors (LGADs)

An extension of the Gluckstern formulas for multiple scattering: analytic expressions for track parameter resolution using optimum weights

Momentum, track angle and impact parameter resolution are key performance parameters that tracking detectors are optimised for. This report presents analytic expressions for the resolution of these parameters for equal and equidistant tracking layers. The expressions for the contribution from position resolution are based on the Gluckstern formulas and are well established. The expressions for the contribution from multiple scattering using optimum weights are discussed in detail

Signals induced on electrodes by moving charges, a general theorem for Maxwell's equations based on Lorentz-reciprocity

We discuss a signal theorem for charged particle detectors where the finite propagation time of the electromagnetic waves produced by a moving charge cannot be neglected. While the original Ramo-Shockley theorem and related extensions are all based on electrostatic or quasi-electrostatic approximations, the theorem presented in this report is based on the full extent of Maxwell's equations and does account for all electrodynamic effects. It is therefore applicable to all devices that detect fields and radiation from charged particles

Suborbital autorotation landing demonstrator on REXUS 29

Current developments in the aerospace industry point towards more frequent interplanetary travel in the future. However, the main focus of developments is on launcher technology, yet the descent of interplanetary probes is of high importance for the success of future missions. Additionally, to the present landing approaches using either a powered descent requiring fuel or a combination of different parachutes, a third method is investigated in this project. The chosen approach is called autorotation and is commonly used in helicopters. When a helicopter suffers a loss of power, it can still land and even choose its landing site without the utilization of an engine. Similar to parachutes, the presented technology can be applied to various atmospheric conditions by modification of rotor and control parameters. Moreover, a rotor in autorotation can provide directional control and thus the choice of a landing site, which is not feasible using a parachute. All these factors make autorotation an interesting option as an entry descent and landing (EDL) technology for interplanetary missions. Our project, Daedalus 2 implements the autorotation landing strategy as part of the REXUS student project campaign under DLR / ESA / SNSA supervision. Since 2018 we are developing the SpaceSeed Mk.2, a technology demonstrator that incorporates a rotor and all necessary technological means to perform an autorotation EDL maneuver from an apogee of 80 km. The mission concept is laid out within the presented paper. This includes the main challenges like miniaturization of the SpaceSeed v2 due to the size constraints of the REXUS rocket or the used sensors for height and position determination. The importance of a technology demonstrator tested on a sounding rocket to prove the feasibility of our presented system is laid out in our publication. Furthermore, the custom development of electrical, mechanical and software sub systems is discussed. Additionally, the planned mission profile will be explained, including flight phases and different activities conducted by the SpaceSeeds during flight. Moreover, the main differences and improvements to Daedalus 1 are being discusse