F.Willeke summarized HERA operation of last week, see transparency
HERA operation was very efficient, only interrupted by trips of the ZEUS
solenoid last Thursday. The positron current was increased steadily. It
is no longer limited by the pressure in the RF section NL.
The delivered integrated luminosity was 3.35pb-1. The peak luminosity
was 2.2 10**31 cm-2 s-1, a new luminosity record.
The proton bunch intensity is close to the design value. The range of the
positron tune is very small. The tune controller is not very stable.
It is difficult to find the best tune for luminosity, background
conditions and polarization.
Polarization was between 30 and 40%. After a proton beam loss it increased
to almost 50%. Finding the right tune is important for polarization.
There were only minor technical problems (magnet trip). Positron injection
is critical and had to be re-optimized.
Some shift crews used a slightly different fill pattern.
H1
Grateful for the long and stable fills. Almost 2pb-1 were written on
tape over the weekend. The HV efficiency was 75%. Chambers could be turned
on soon after the beginning of a fill. There were some periods of
background spikes causing HV trips. Ready for higher beam currents.
Would like to change the spin helicity during the
maintenance day in March.
ZEUS
The solenoid has been off since Thursday. Diagnostics was added to find
the
reason for the magnet trips. The fast discharges are caused by trips
of the power supply. It was disconnected and operated without the
solenoid. A controller was exchanged yesterday. The power supply
has been running stably since yesterday evening. Today it will be
re-connected
to the magnet. The plan is to ramp up the solenoid during the next
luminosity fill and to do a full calibration of the calorimeter (about 2h)
after the beam dump.
HERMES
Very good data taking. The first 1/2h of a fill is usually lost due to
high backgrounds. Background conditions improve when the tune is changed.
The target valve still closes during proton acceleration (being
investigated by M.Bieler).
Thursday around noon a high dose rate was accumulated when the positron
beam was dumped.
Schedule
Continue luminosity operation with 120 bunches.
(Increasing the number of bunches will be discussed next week.)
HERMES high density target runs will start at Ie=13mA.
Changing the position of spin rotators will be discussed next week.