如何禁止（disable） optical photons

1. 环境变量 GATE_USE_OPTICA，在 gate_v3.1.0/env_gate.csh 文件里面有：

setenv GATE_USE_OPTICAL 1
if ( ${?GATE_USE_OPTICAL} ) then

if ( -X xml2-config ) then
echo "Transport and generation of optical photons is enabled"
else
echo "WARNING: xml2-config was not found in the path."
echo " transport and generation of optical photons has been disabled"
echo " "
echo " When optical transport is needed: install the libXML2 development packages "
echo " (which should include xml2-config) and rerun the configuration script. It is "
echo " also possible to set the linker and compiler flags for libXML2 by hand in "
echo " GNUmakefile and set GATE_USE_OPTICAL to 1 after running this configuration "
echo " script."
setenv GATE_USE_OPTICAL 0
endif

else
echo "Transport and generation of optical photons is disabled"
endif

改成 setenv GATE_USE_OPTICAL 0

2. /gate/physics/optical/enable 1 打开 optical photons，改成0应该是禁止吧。