Background:
The non clusterized hydrogen gas inside the machine is pumped out from a
differential pumping system. Even so, a fraction of this gas diffuses into the Antiproton Accumulator.
The flow of this gas, called Q(AA), causes the annihilation of antiprotons in regions of the beam pipe
not monitorized from the detectors. This represents a waste of precious antiprotons!
A result of our upgraded Gas Jet machine is that Q(AA) for E835 = 1/10 of QAA for E760.
The efficiency of the machine or Jet Target Efficiency is the ratio between the number
of hydrogen atoms seen by the antiprotons passing only through the 7 mm thick target and
the number of hydrogen atoms seen by the antiprotons during their whole path in the Antiproton Accumulator.
We have a JTE = 95%.
This is more than a factor 2 better than E760
(JTE = 40%).
For an instantaneous luminosity of 1E31 cm^(-2)s^(-1) = 36 nb^(-1)/h this means that we use 0.3 mA/h
of antiproton beam, instead of 0.7 mA/h of E760, or, in other words,
we get an integrated lumonisity of 101 nb^(-1)/mA instead of 54 nb^(-1)/mA of
E760.
