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Enhancement factor of the event rate

CAIN normally produces macro-photons such that the expected number of macro-photons per macro-electron is equal to the expected number of real photons per real electron. In some cases, however, too many macro-photons are created causing the memory overflow, or the statistics is too poor due to a small number of macro-photons. To solve this problem, a variable WENHANCEMENT=tex2html_wrap_inline7990 is introduced in the CFQED command.

When tex2html_wrap_inline8006, more macro-photons are created. They have the weight smaller than that of the parent electron/positron by the factor 1/tex2html_wrap_inline7990. However, the recoil of electron/positron is taken into account only with the probability 1/tex2html_wrap_inline7990 so that their statistical property does not depend on tex2html_wrap_inline7990.

When tex2html_wrap_inline10458, the event generation goes the same as in the case tex2html_wrap_inline7990=1, but the final photons are stored in the memory only with the probability tex2html_wrap_inline7990. The recoil of electron/positron is taken into acount regardless the photon is stored or not.

Thus, if there is no bug, tex2html_wrap_inline7990 does not cause any physical change.

Toshiaki Tauchi
Thu Dec 3 17:27:26 JST 1998