Problem in Touschek lifetime calculation

[ranamonikaa]

Hi,
I am calculating Touschek lifetime in elegant for a 6 GeV electron storage ring. I want to see the variation of Touschek lifetime with energy of the electron beam. I started with 200 MeV beam energy to 6 GeV energy in steps. I am getting inconsistent Touschek lifetimes for lower energies. The value of rf voltage required is calculated by considering the synchrotron tune constant for all the energies. For phase calculation in rfca, SR loss is changed accordingly. For Touschek lifetime calculation, the command I used was:
touschekLifetime -twiss=hbsrs200.twi -aperture=hbsrs200.mmap hbsrs200-mmap.lt -charge=0.4 -coupling=0.01 -rf=volt=0.2195,harm=1520

the result that I am getting is:
pCentral (m$be$nc) = 3.913902e+02 Sdelta0 = 3.063069e-05 ex0 ($gp$rm) = 1.649478e-13
coupling = 1.000000e-02 emitx (m) = 1.633146e-13 emity (m) = 1.633146e-15
Sdelta = 3.063069e-05 Particles = 2.496603e+09 Charge (nC) = 4.000000e-01
sigmaz (m) = 7.892135e-05 tLifetime (hour) = inf deltaLimit = 0.000000e+00

I am not able to figure out why I am getting infinite Touschek lifetime. I am attaching the files below. Kindly help me in identifying where I am making mistakes.

Thank You.
Monika

[michael_borland]

Monika,

I don't think you are making any mistakes. It appears that the emittance is so low that you are in the frozen-beam regime, where the Touschek lifetime goes up rapidly because there is insufficient transverse momentum to cause scattered particles to exceed the longitudinal momentum acceptance (which is large).
https://journals.aps.org/prab/pdf/10.11 ... .12.120701

--Michael