HVS 2/26/99
For Colliders,the term "Luminosity" is Defined to be Interraction Rate 
per unit Cross Section, and is parameterized in general as: (Edwards&Syphers)

                     (f)*(N+)*(N-)             with f  = collision frequency
        LUM =   _______________________             
               (4pi)*(capsigX)*(capsigY)            N+ = number of + particles
                                                         per collision bunch

                                                    N- = number of - particles
                                                         per collision bunch

                                             capsigX   = Quadrature convolved
                                                         horizontal spot size.

                                             capsigY   = Quadrature convolved
                                                         vertical spot size.

For multibunch machines like PEPII, it is useful to restate this in terms
of total stored current and the number of bunches stored. 

Consider the relation:

	I- = (N-)*(q)*(Nb)*(f0)                with I- = total stored current
                                                         in - beam (amperes).

such that					   N-  =  as above.
                  I-
       N- = _____________               	   q   =  particle charge;
             (q)*(Nb)*(f0)                             1.6e-19coul/particle

						   Nb  =  Number of buckets
and additionally that                                     having this N-

      f = (Nb)*(f0)				   f0  =  Go-around frequency.


Substituting these last two relations into the definition asserted above,
one finds:

                         1                   (I+)*(I-)
	LUM   =  ________________  *  ________________________
                 (4pi)*(q^2)*(f0)     (Nb)*(capsigX)*(capsigY)

                         ^                       ^
                         |                       |
               Constant for given      Parameters which vary with
               e+/e-  collider.        machine performance.