CJC currents

CJC2 current history since 2002:

Method:

Subtract 15 μA pedestal for CJC2 (constant since 2002).
Subtract SynRad = 1.2 μA per mA of e⁺.
When the beam is well steered (flat in x and y up to 100 m), only the irreducible backscattering from ABS4 remains.
Normalize to e-gas and p-gas contributions as determined in Sep 2002, as function of beam currents.

CJC1 with 27.6 GeV e⁺ only:

The cyan point taken on 1.12.2003 shows a significant improvement.

Analysis of isolated bunch-trigger data by C.Niebuhr reveal that the e-gas contribution is much lower than in 2002 (improved pumping North Left), while the SynRad contribution is always at the same level (backscattering from ABS4).

CJC1 with 27.6 GeV e⁺ only:

24.9.2003: first test with beam after the '03 shutdown (magenta).
After 3 hours of beam steering an collimator optimization
we reached the lowest CJC1 current ever: 21 μA at 9.7 mA.
CJC2 was also fined with 27 μA.

We took data triggering on isolated bunch #200 to separate e-gas tracks (N>10) from random SynRad hits (N_hit<5).
Carsten Niebuhr analyzed the drift time distribution:

Compare to our first background report from Oct 2002:

z- and phi-distribution of CJC hits for track-events and SynRad events:

The dip at -z is in marked contrast with the backward peak observed in 2002
and can be attributed to the lead shielding now installed under the BST Repeater.

Last modified: Mon Jan 12 14:30:00 MET 2004 by Daniel Pitzl