function [deltamin, deltamax...
]=momentum_aperture_at(THERING,...
deltalimit,... [min max]
initcoord,... [x y] initial coordinate
delta,...
precdelta,...
deltastepsize,...
splits,... % number of splitting
split_step_divisor) % divide the step size at every split
following the ELEGANT routine:
Start with ? = 0, i.e., zero momentum offset.
2. Track a particle to see if it gets lost. If so, proceed to step 4.
3. Increase ? by step size ?? and return to step 2.
4. If no splitting steps remain, proceed to the next step. Otherwise:
(a) Change ? to deltas ? sb??., where ?s is the largest ? for which the particle survived, and sb is the steps_back parameter.
(b) Divide the step size by split_step_divisor to get a new step size ??.
(c) Set?=?+??.
(d) Decrement the ?splits remaining? counter by 1.
(e) Continue from step 2.
5. Stop. The momentum aperture is ?s
ex: [deltamax]=momentum_aperture_at(THERING,0.1,[10^-6 10^-6],0,0,0.01,3,10,100)
ex: [deltamin]=momentum_aperture_at(THERING,-0.1,[10^-6 10^-6],0,0,-0.01,3,10,100)0001 function [deltamax]=momentum_aperture_at(THERING,deltalimit,initcoord,delta,precdelta,deltastepsize,splits,split_step_divisor,nturns) 0002 % function [deltamin, deltamax... 0003 % ]=momentum_aperture_at(THERING,... 0004 % deltalimit,... [min max] 0005 % initcoord,... [x y] initial coordinate 0006 % delta,... 0007 % precdelta,... 0008 % deltastepsize,... 0009 % splits,... % number of splitting 0010 % split_step_divisor) % divide the step size at every split 0011 % 0012 % following the ELEGANT routine: 0013 % Start with ? = 0, i.e., zero momentum offset. 0014 % 2. Track a particle to see if it gets lost. If so, proceed to step 4. 0015 % 3. Increase ? by step size ?? and return to step 2. 0016 % 4. If no splitting steps remain, proceed to the next step. Otherwise: 0017 % (a) Change ? to deltas ? sb??., where ?s is the largest ? for which the particle survived, and sb is the steps_back parameter. 0018 % (b) Divide the step size by split_step_divisor to get a new step size ??. 0019 % (c) Set?=?+??. 0020 % (d) Decrement the ?splits remaining? counter by 1. 0021 % (e) Continue from step 2. 0022 % 5. Stop. The momentum aperture is ?s 0023 % 0024 % ex: [deltamax]=momentum_aperture_at(THERING,0.1,[10^-6 10^-6],0,0,0.01,3,10,100) 0025 % ex: [deltamin]=momentum_aperture_at(THERING,-0.1,[10^-6 10^-6],0,0,-0.01,3,10,100) 0026 0027 %disp([delta splits]) 0028 0029 if ( delta>=0 && delta<deltalimit) || ( delta<=0 && delta>deltalimit) 0030 0031 if splits>-1 0032 0033 % track for this delta 0034 0035 [~, LOSS] =ringpass(THERING,[initcoord(1) 0 initcoord(2) 0 delta 0]',nturns); 0036 0037 if LOSS~=1 % if NOT LOST go to next step 0038 0039 [deltamax... 0040 ]=momentum_aperture_at(THERING,... 0041 deltalimit,... [min max] 0042 initcoord,... [x y] 0043 delta+deltastepsize,... % delta center 0044 delta,... 0045 deltastepsize,... 0046 splits,... % number of splitting 0047 split_step_divisor,... 0048 nturns); 0049 0050 else % if LOST reduce stepsize 0051 0052 [deltamax... 0053 ]=momentum_aperture_at(THERING,... 0054 deltalimit,... [min max] 0055 initcoord,... [x y] 0056 precdelta+deltastepsize/split_step_divisor,... % go back to previous delta center and increase of smaller step 0057 precdelta,... 0058 deltastepsize/split_step_divisor,... 0059 splits-1,... % number of splitting 0060 split_step_divisor,... 0061 nturns); 0062 0063 end 0064 else 0065 0066 % no splitting steps remain 0067 deltamax=delta-deltastepsize; 0068 0069 end 0070 0071 else 0072 % limit reached 0073 deltamax=delta; 0074 end 0075 0076 0077 return; 0078 0079 0080