Target Density Corrections - Luminosity Scans

Target Density Corrections refer to factoring in the change of density that
occurs for liquid targets that are in the path of the electron beam. As the liquid target heats up from the
beam, localized changes in density occur
(often referred to as a "boiling effect"). To correct for this we've
plotted the yield vs. increasing current, otherwise known as a Luminosity scan.


The Yield and Error were calculated by:

Y = (Pre-Scale)*(# of electron events)/ (Track_eff*LiveTime*Charge)

Error Y = Y / sqrt( # of electron events)

To obtain the # of electron events, I applied cuts on the Calorimeter (shower
track) to get a clean sample of electrons without pions. These cuts were:

Cer>2
Cal>0


Where Cer refers to the # of photoelectrons produced in the Cerenkov detector.
For electrons there are usually 10 whereas pions are usually at zero
photoelectrons.
Cal refers to the energy received in the calorimeter divided by the energy of
the outgoing particle (Ecal/E'). We expect electrons to deposit all their
energy in the calorimeter so Cal~1.

On this page, we plotted Luminosity scans for LD2(1,2), LH2 and two
solid targets, C and Fe. The solid targets were
scanned for comparison and do not show evidence of any "boiling" as
expected by their fairly constant slope. For LD2, the yield decreases with
current which indicates some change in density.

Here all Luminosity Scans have been plotted in the kinematics of:

E'= 2.0 GeV  and Theta = 20.00 Degrees

Slope and error has been calculated in % per 100uA for each scan.  

The runs used to make these scans are as follows:

LD2(1): 52544-9
LD2(2): 52691, 52694-8 
LH2:    52537-52542
 C:     52550-5 
 Fe:    52687-52690

LD2 (1)

LD2(2)

LH2

Carbon

Iron