Draft: Yezhenyu btof 20210520

Add Barrel TOF

compact/tof_barrel.xml

@@ -93,7 +93,7 @@
         <barrel_envelope inner_r="BarrelTOFRadius" outer_r="BarrelTOFRadius + 30.0*mm" z_length="BarrelTOFTotalLength +1.0*mm "/>
         <rphi_layout phi_tilt="0.17506" nphi="BarrelTOFModulesNPhi" phi0="0." rc="BarrelTOFRadius + 10.0 * mm" dr="0.0 * mm"/>
         <z_layout dr="4.0 * mm"
-                  z0="BarrelTOFLength/2 - BarrelTOFModuleLength/2"
+                  z0="(BarrelTOFLength - BarrelTOFModuleLength)/2"
                   nz="BarrelTOFModulesNZ"/>
       </layer>
     </detector>