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Matlab software used for design of the 2D-transverse-emittance-meter system based on the slits method.

par BROSSARD Julien - 4 novembre 2011

This article present the matlab software used for the design of a 2D-transverse-emittance-meter system based on the slits method. This software has been developped and used by J. Brossard for PHIL accelerator.

The formulae used in this software are listed and explained in the PHIL’s note N°2011-011 available here (in French).

For all questions or comments, please contact the author : J. Brossard.


In case of utilisation, modification, diffusion of this software, you would be kind to include the following sentence in all document, note, paper, webpage dealing with the utilisation of this software : This software has been initialy written by Brossard Julien ( from Laboratoire de l’Accélérateur Linéaire (IN2P3/CNRS/Université Paris-Sud XI, Orsay). The initial version of this software is freely available on this web page : http://phil/spip.php?article145


---> For french documents :

En cas d’utilisation, modification, diffusion de ce code, merci d’inclure la phrase suivante dans tout document, notice, rapport, site internet relatif à l’utilisation de ce code : Code initialement rédigé par Brossard Julien ( du Laboratoire de l’Accélérateur Linéaire (IN2P3/CNRS/Université Paris-Sud XI, Orsay). La version initiale du code est librement disponible à cette adresse : http://phil/spip.php?article145

-------- Download --------

In order to used this sotware, you have to :

  1. download this file : "Transverse_Emittance"
  2. unzip this file
  3. run matlab (in the directory where the file has been unziped) and type (under matlab command window) "Transverse_Emittance _Meter_Design"

Remark : this code has been written and used under Linux version of Matlab (version (R2008a)). If you use an other matlab version or an other exploitation system, you may have to introduce little modifications in the code.

-------- How the code works ?--------

After launching the "Transverse_Emittance _Meter_Design.m" code (from matlab command window) the software will open 3 different windows (Figure 1, figure 2 and figure 3). At the beggining of the run, some informations will be summarised on the matlab command windows :

  • Distance between slits and screen : Ld = 230 mm (see figure below)
  • Number of slits : Nslits = 28
  • Thickness of the slits : e = 3.5 mm (see figure below)
  • Domain in (w,d) space where the solutions will be search :
    • 0.05 < d (mm) < 1 (see figure below)
    • 0.2 < w (mm) < 3 (see figure below)
  • Assumed bunch length : sigt = 5 ps

(for you own system, you have to modify these values in the code itself).

In the current version of the code, the different cases studied are summarized in Table 1 :

Table 1
case n°1 E (MeV) normalized rms transverse emittance transverse beam size at slits entrance (mm)
1 5 1 3
2 2 3.5
3 5 4
4 10 5
5 10 10 6
6 15 7
7 20 8

Figure 2 shows the (d,w) space location where the constraints (see PHIL note n°2011-011) are individually (column 1 to 4) and all together satisfied (column 5), for all cases of Table 1 (case 1 in line 1, case 2 in line 2...). The last column shows the maximal beam intensity value (in A) in the (d,w) domain where all constraints are satisfied.

Figure 2 :

Figure 3 shows the (d,w) domain where the system is able - for each initial cases (listed in Table 1) - to reconstruct transverse-emittance (which means that all the cnstraints are satisfied). On this figure (obtained for the particular studied system), you can see that the location where the device could be used for all initial cases (of Table 1) is a small ribbon around w=1.5 mm. On this figure, the white cross shows the location (d_sel,w_sel) where the maximal beam charge supported by this system (for each cases of Table 1) will be evaluated.

Figure 3 :

Figure 1 shows the maximum bunch charge (conversion of the beam intensity assuming a bunch length of 5 ps) supported by the system (with d=d_sel, and w=w_sel) for each cases of Table 1.

Figure 1 :