MainPage:Nuclear:KaonDetector:Simulations:Codes

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General commands

Mirrors

There are two ways to work with mirrors on GEMC. The first one is to define the mirror in the definition of the material, and recompile the GEMC. But the easiest way is to specify the mirror in the "identifiers" field of a geometry definition, in the 'pl' file.

The parameters that can be specified using the identifiers field are:

• WithSurface: 1 (0: dielectric_metal; 1: dielectric_dielectric)
• With Finish: 1 (0: polished; 1: ground)
• Refraction Index: 1030000 (r*1M - this corresponds to 1.03)
• With Reflectivity: 550000 (R*1M - this corresponds to 0.55)
• With Efficiency: 400000 (E*1M - this corresponds to 0.40)
• WithBorderVolume: HTTC (border volume, necessary, must be at the end)

The way to use it in the detector definition is:

$detector{"identifiers"} = "Mirror WithSurface: 1 With Finish: 1 Refraction Index: 1030000 With Reflectivity: 1000000 With Efficiency: 1000000 WithBorderVolume: daughter10";

The code that reads the of the mirror definition of the geometry is inside the MDetectorConstruction.cc. More details in how the GEMC reads these parameters can be understand from looking at this file.

First Simulations on GEMC

For the study of the Kaon Aerogel Cerenkov Detector in the SHMS, some simulations are being prepared using GEMC code. GEMC is a code based on the Geant4.

A first model of the detector was constructed using the standard library of the GEMC, with the standard materials and geometries. The following pictures show this first simplified model of the detector.

First Kaon Aerogel Detector geometry for the simulations on GEMC

First simulation on GEMC: a single Pion passing through the aerogel detector. Its velocity is lower than the threshold velocity of the aerogel, no Cerenkov radiation was emitted.

Layers of the Aerogel Detector simulated in GEMC (not scaled). From the right to the left (in the path of the particles): honeycomb first skin (Aluminum), honeycomb inside (Air), honeycomb second skin (Aluminum), aerogel, diffusion box inside (Air) and upper plate (Aluminum).

Setting the GEMC code to work with material optical properties, a high momentum Pion was generated to pass through the aerogel. The following pictures shows the first results on these simulation. The end plate was set to absorb the photons, so it was possible to see the cone of photons generated by the Cerenkov phenomena.

First Cerenkov radiation generated in Aerogel Detector, on GEMC simulation

View of the back of the detector. Simulation of a Pion passing though the detector, with velocity higher than the threshold of the Cerenkov phenomena. So a cone of photons was created as a result of this phenomena.

Back view of the detector. An electron was also created inside the detector, also generating photons due to Cerenkov phenomena.

Side view of the detector. The photon absorption on the end plate is illustrated by points.