Brief History: HERA and HERA-B Target

Since the first days of HERA operation the progress of the HERA-B target was closely related to the steadily ongoing development and improvement of the HERA proton ring.

1992:

Shortly after HERA produced first e-p luminosity with 10 proton bunches and an integrated current of 1.5 mA first tests with the HERA-B target were carried out in autumn 1992. A simple test setup was installed in a freearea in the west right straight section at WR118. With one wire short term rates of 40 kHz with an efficiency up to 8 % have been achieved.

1993

HERA operates with 90 p-bunches and a current of 15 MHz. The target setup was significantly improved. With the four installed wires (movable pairs of wires at opposite beam sides with fixed distance) rates up to 8 MHz have been achieved. With a very simple setup of small drift chambers tracks pointing to the target has been observed.

1994

HERA is now operating with 50 mA of protons in 170 filled bunches. The natural lifetime of the p-beam exceeds 1000 h. To reach 40 MHz rate it was necessary to reduce the lifetime to less than 50 h; this didn't affect the HERA luminosity operation.

1995

The improved target mechanics allowed the independent movement of four wires from all four sides. Major improvements have been made in the automatic target steering, the monitoring and logging of external data (e.g. HERA information).

1996

HERA fills up to 80 mA protons in 180 bunches. The target with now 8 independent movable wires is mounted on the vessel of the HERA-B vertex detector system (VDS) and operated at the final location at WR09 with the final optics parameter. In long term high rate target operation the functionality and reliability of the HERA-B target has been demonstrated. A major milestone was the successful reduction of target induced backgrounds by means of the HERA collimator system, which opened the way for a successful corporation with the other HERA experiments. The distribution of the interactions along the target wire was measured with the vertex detector test setup.

1997

HERA exceeds 100 mA of filled proton current. The target is now nearly continuously in operation. Detailed investigation of the contributions of individual bunches gave solicitous results concerning the non proton bunch related interactions. A new wire insertion procedure helped to increase significantly the target running efficiency and to reduces the proton background and eases the optimization.