VTX readiness for RUN15 Y. Akiba

VTX in RUN14 VTX worked very well during RUN14. Repair of damaged pixel ladders completed before RUN14 Only 1 ladder, B1L11, in the 2nd layer (5% acceptance) was not working. The ladder stop working after VTX was installed in the IR Stable operation of pixel during the run 20 billion Au+Au events recorded in narrow BBC trigger However, 7 stripixel ladders stopped holding bias voltage in the 1 month of the Au+Au run. VTX was moved to the new VTX lab in Physics after the run to investigate the problem. FVTX also needs to remove F/VTX from the IR to fix some issues of the detector.

Pixel maintenance Kurosawa-san and Sumita-san came to BNL for maintenance of pixel in August. All ladders tested and found that they are same status as the end of RUN14 B1L11, which was not working duirng RUN14, was found dead. We decided to keep it as it is, since replacing it requires de-assembly of the entire B1 West barrel B1L11 is at the edge of the Central Arm acceptance

Pixel Chip Map (August) Slides by Sumita-san No change from RUN14 commissioning except for 1 chip

Stripixel Cause of the stripixel bias voltage problem was found Water condensation leaking into VTX Some of the ROCs were damaged by water All ladders that were damaged were repaired Damaged bus cables and ROCs were replaced All ladders were tested after strip barrels are re-assembled

Pixel repair (leak, mainfold) Leak were found in the cooling manifold and one of the ladder Manifold was remade, using stainless steel tees and angles. The leaky ladder was replaced by a spare sent from RIKEN Sumita-san worked on this in October – November All ladders are tested by Sumita-san again after pixel barrels are re-assembled.

Pixel Chip Map Slides by Sumita-san No change in the status

Additional test of Pixel Slides by Nakagomi-san and Asano-san After West F/VTX was assembled, two stripxel ladders stop working. This problem was “fixed” by applying pressure to the contact point of the bus cable and the read-out board This could affect nearby pixel ladders. Asano-san/Nakagomi-san tested nearby pixel ladders and found that they were fine.

Making VTX waterproof Extensive work on the cooling tubes and gas enclosure to prevent water leak in future “walk-through” review of the detector on 10/29 before re-installation The plan is to keep the detector at the IR to the end of RUN16

VTX status West VTX was re-installed in the IR on 11/13 East VTX is in the VTX lab in physics Needs final test before shipping to the IR Installation is ~2 weeks from now; delayed by MPC-EX work