Telescope Resolution Simulation

Calculator class for telescope track resolution using the General Broken Lines formalism.

This small collection of scripts provides a simple interface for the simulation of telescope resolutions including the effects of multiple scattering in the telescope planes and the surrounding air.

Features

• Error propagation of track extrapolation uncertainty using GBL
• Includes scattering in material, estimated via the PDG Highland formula
• Automatically accounts for air between the telescope planes
• Automatic placement of the thin scatterers at correct positions
• Planes ordered automatically in z for correct GBL trajectory building
• Radiation length for some common materials are defined in utils/materials.h

Installation

• Install and source ROOT

• Install GBL (from https://www.wiki.terascale.de/index.php/GeneralBrokenLines)

  svn checkout http://svnsrv.desy.de/public/GeneralBrokenLines/tags/V01-16-04/cpp GeneralBrokenLines
  cd cpp
  mkdir build && cd build/
  cmake ..
  make && make install
  

• Export the GBL library path:

  export GBLPATH=/path/to/gbl/installation
  

• Compile this code:

  mkdir build
  cd build
  cmake ..
  make
  

Prepare your own telescope simulation

• All telescope assemblies are stored in the devices directory.
• Take one of the provided examples, adapt it to your needs and add the executable to the CMakeLists.txt file in the devices directory in order to compile the executable.
• Have a look at the devices/tscope_datura.cc example for some explanatory comments on how to build the telescope assembly.

Further hints:

• The resolution can only be evaluated at a previously defined plane. This can either be a plane with measurements, a scatterer, or a plane with no material attached. They can be defined as follows:

gblsim::plane measurement(position, material, TRUE, resolution); - plane with measurement and scattering material

gblsim::plane scatterer(position, material, FALSE); - plane with scattering material but no measurement

gblsim::plane reference(position, 0, FALSE); - plane with zero material and no measurement (simple reference point)

• The material budget is always given as fractions of radiation lengths. Thus, divide your material thickness by its radiation length, and add up different materials as linear sum, e.g.

  // MIMOSA26 telescope planes consist of 50um silicon plus 2x25um Kapton foil:
  double MIM26 = 50e-3 / X0_Si + 50e-3 / X0_Kapton;
  

• The resolution is always given as intrinsic resolution of the respective sensor in units of micrometer.