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Changes in the RADIATION DAMPING routine in SixTrack

Changes in the RADIATION DAMPING routine in SixTrack. Elena Quaranta Roderik Bruce. Outline. Some modification has been done to the code… …why? …how? …where? any inputs changed? new outputs added? conclusions. … why ?. SixTrack. r adiation damping routine.

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Changes in the RADIATION DAMPING routine in SixTrack

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  1. Changes in the RADIATION DAMPING routine in SixTrack Elena Quaranta Roderik Bruce

  2. Outline • Some modification has been done to the code… …why? …how? …where? • any inputs changed? • new outputs added? • conclusions

  3. …why? SixTrack radiation damping routine can track particles starting with a certain energy offset with respect to the nominal energy + 1 routine (by R. Bruce & S. Redaelli) …to study the effect of emission of synchrotron radiation particles are tracked taking into account the energy loss on every turn 6.71 keV/turn (scaled with the forth power of energy) !! more than 1million turns before particle hit the IR3 TCP (see CWG on March 18, 2013) Huge computing time (≈4 days for a 64 particles simulation)

  4. …how? Case 1: apply large energy loss 6.71 MeV/turn x Case 2: apply small energy loss 6.71 keV/turn To guarantee at least 2 synchrotron oscillations before particle reach IR3 TCP Solution found: energy loss dependent on x-coordinate at IR3 TCP

  5. …where? ! RADIATION DAMPING at IR3 TCP if(i.eq.1423) then if (iturn.eq.1) then do j=1,napx eLossLarge(j)=1.d0 enddo endif if (iturn.gt.1) then xTCP3 = nsig_tcp3 * sqrt(tbetax(i)*myemitx0) do j=1,napx if (eLossLarge(ipart(j)).eq.0.d0) then ejv(j) = ejv(j) - 6.71d-3*(ejv(j)/7000000.d0)**4 write(998,*)ipart(j)+100*samplenumber,iturn,6.71e-3,(ejv(j)-myenom)/myenom, xv(1,j) else … if we are at the IR3 TCP… …apply small energy loss to particle j …and at the first turn create array: 1=> do large energy loss, 0=> do realistic small energy loss If the value of the array is 0 for particle j ... If the value of the array is 1 for particle j… x-coordinate of IR3 TCP debugging output

  6. …where? … if (xTCP3 - 1.d-3*abs(xv(1,j)).LE.100.0d-6) then ! ejv(j) is the energy in MeV for particle j ejv(j) = ejv(j) - 6.71d-3*(ejv(j)/7000000.d0)**4 eLossLarge(ipart(j))=0.d0 write(998,*)ipart(j)+100*samplenumber,iturn,6.71e-3,(ejv(j)-myenom)/myenom, xv(1,j) else ejv(j) = ejv(j) - 6.71*(ejv(j)/7000000.d0)**4 write(998,*)ipart(j)+100*samplenumber,iturn,6.71,(ejv(j)-myenom)/myenom, xv(1,j) endif endif enddo endif endif debugging output …if particle j is within 2 synchrotron oscillations from IR3 TCP… …apply small energy loss… …apply large energy loss …also for all the consecutive turn for particle j ..if farther away than 2 synchrotron oscillations from IR3 TCP… debugging output

  7. any input changed? COLLIMATION (1) .TRUE. (2) 1 7000000 (3) 4 4.3 .0015 0. 0. "startingConditions_new.dat" 1.129E-4 75.5 … name of the external file set to 4 = “read from external file” • No new inputs are required • In the fort.3: external file containing both betatron and longitudinal phase space coordinates for each particle to be read by SixTrack to set the particle starting conditions

  8. new outputs added? - particle ID - number of turn - energy loss (6.71 keV or 6.71 MeV) - energy offset - x-coordinate at IR3 TCP fort.998 • No new “real” outputs created • 1 debugging output:

  9. Conclusions New routine 3.5 hours for 640 particles simulation Old routine 4 days for 64 particles simulation • The validation of the new routine is still on going: the comparison between the new simulations and the results from the previous ones is now under studied. • However, the computing time is significantly reduced using the new version of the routine:

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