The OPAL Discussion Forum

["Zhang Hui (PSI)" <hui.zhang AT psi.ch>]

Dear Andreas

 

As I reported to you last Friday, a problem aroused from the simulation for the COMET centrum regarding a pair of vertical collimators.

 

The vertical collimators are defined by the following parameters

 

vcu: ccollimator, xstart=x1, xend=x2, ystart=y1, yend=y2, zstart=-z1, zend=-z2, …;

vco: ccollimator, xstart=x1, xend=x2, ystart=y1, yend=y2, zstart=z2, zend=z1, …;

 

Then the definition of the line.

 

L1: Line = (…, vcu, …., vco, …);

 

After the run, two loss data will be generated, vcu.loss and vco.loss. It turns out that vco.loss contains may particles in the range between –z1 and –z2, besides the particles between z2 and z1.

 

The registration of the loss data is done after each time step. In a specific step, if there are particles hit on both collimators, then they will all be registered by vco.loss, which lies behind the collimator vcu on the line L1. On the other hand, the loss data vcu.loss registers particles only between –z1 and –z2.

 

I clearly see the difference in vco.loss, after changing the time step. The vcu.loss is unchanged.

 

I have not yet found a solution to the problem. If you have any suggestion, please keep me informed.

 

Best regards, Hui

 

__________________________________________
Paul Scherrer Institut
Dr. Hui Zhang
WBGA/C34
CH-5232 Villigen PSI

Telefon: +41 56 310 53 98
E-Mail: hui.zhang AT psi.ch