InducedTransfer

Transfer with induction from nearby charge carriers
Status Functional
Maintainers Simon Spannagel (simon.spannagel@cern.ch)
Input Objects PropagatedCharge
Output Objects PixelCharge

Description

Combines individual sets of propagated charges together to a set of charges on the sensor pixels by calculating the total induced charge during their drift on neighboring pixels by calculating the difference in weighting potential. This module requires a propagation of both electrons and holes in order to produce sensible results and only works in the presence of a weighting potential.

The induced charge on neighboring pixel implants is defined the Shockley-Ramo theorem [@shockley, @ramo] as the difference in weighting potential between the end position $x_{final}$ retrieved from the PropagatedCharge and the initial position $x_{initial}$ of the charge carrier obtained from the DepositedCharge object in the history. The total induced charge is calculated by multiplying the potential difference with the charge of the carrier, viz.

$$Q_n^{ind} = \int_{t_{initial}}^{t_{final}} I_n^{ind} = q \left( \phi (x_{final}) - \phi(x_{initial}) \right)$$

The resulting induced charge is summed for all propagated charge carriers and returned as a PixelCharge object. The number of neighboring pixels taken into account can be configured using the distance parameter.

Parameters

  • distance: Maximum distance of pixels to be considered for current induction, calculated from the pixel the charge carrier under investigation is below. A distance of 1 for example means that the induced current for the closest pixel plus all neighbors is calculated. It should be noted that the time required for simulating a single event depends almost linearly on the number of pixels the induced charge is calculated for. Usually, for Cartesian sensors a 3x3 grid (9 pixels, distance 1) should suffice since the weighting potential at a distance of more than one pixel pitch often is small enough to be neglected while the simulation time is almost tripled for distance = 2 (5x5 grid, 25 pixels). To just calculate the induced current in the one pixel the charge carrier is below, distance = 0 can be used. Defaults to 1.

Usage

[InducedTransfer]
distance = 1