Message: Problems with GPS and position and direction distributions? Not Logged In (login)

## Problems with GPS and position and direction distributions?

Keywords: GPS, position and direction distributions, biasing, usr-defined histograms
Forum: Particles
Date: 17 Oct, 2007
From: Shahrokh <Shahrokh>

 ```Hi, I have some questions about to define position and angular distributions by using GPS, as follows: When I execute my application, the particles traverse a plane. For each particle traversing this plane the position (X and Y coordinates), direction ( X, Y and Z components of momentum direction ) and energy are stored in six 1-D histograms by using AIDA that these horizontal axes are the position coordinates, the components of momentum direction and energy, respectively in which the particle incident upon the plane. Afterwards, I want to define these distributions (positions, directions and energy) by using GPS commands in user-defined histograms or biasing and save these commands in a macro file and then I execute again from this planar source by having these distributions in this macro file. In the following, I divide my works in three steps, the definition of energy, position and angular distributions from these six 1-D histograms by using GPS commands: --------------------------- 1- Energy distribution: I can initialize this energy distribution (1-D histogram) by using the commands following: /gps/ene/type User /gps/hist/type energy /gps/hist/point ... ... /gps/hist/point is followed by its two arguments - the upper boundary of the bin and weight of the bin. I think I do it correctly. In your opinion, is it correct? --------------------------- 2- Direction distribution: For the initialization of the direction distribution by using GPS, firstly I must get angular distribution (Phi and Theta) from momentum direction distribution. For this purpose, after getting X, Y and Z components of momentum direction, I can calculate Phi and Theta angles with the following formulas: Phi = Arctan(Py/Px) Theta = Pi - Arccos(Pz) After getting two 1-D histograms from Phi and Theta distributions, I can use the following commands: For Theta: /gps/ang/type user /gps/hist/type theta /gps/hist/point ... ... ... For Phi: /gps/ang/type user /gps/hist/type phi /gps/hist/point ... ... ... I think I do it correctly. In your opinion, is it correct? --------------------------- 3- Position distribution: The position distribution in this plane is that many particles emanate from a region in the rectangular shape and a few particles emanate from the out of this region. At now, I want to define a planar source by using this position distribution, but I do not know how to do it. I thought that I could do it by using the commands as follows: /gps/pos/type user /gps/hist/type biasx /gps/hist/point ... ... ... Unfortunately, I did not see the command as similar to /gps/pos/type user. Although I do not exactly understand the concept of biasing. How can I do it? Please tell me the role of biasing. In the other hands, is it correct that I bias distributions by using two 1-D histograms of X and Y components, synchronously? Does it superimpose into the rectangular region? Please guide me, Shahrokh. ```

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1 Re: Problems with GPS and position and direction distributions?   (Shahrokh - 20 Oct, 2007)
3 Re: Problems with GPS and position and direction distributions?   (Fan Lei - 02 Nov, 2007)
 to: "Problems with GPS and position and direction distributions?"
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