Wire-Embedded TCTW collimators


One tertiary collimator (TCTPH.4R5.B2) and a collimator for physics debris (TCL.4L5.B2) were replaced on Beam 2 in IR5 by tungsten collimators with in-jaw wires in 2016. The goal was to demonstrate that it is possible to compensate or alleviate the Beam-Beam Long-Range (BBLR) effects by powering the DC wires in the framework of the HL-LHC project. In addition in 2017, two other collimators were replaced in Beam 2 in IR1 (TCTPV.4R1.B2 and TCLVW.AL5.B2)

In 2018 MDs a reduction of beam losses due to a partial BBLR compensation using the DC wires installed in the collimators was successfully demonstrated. The experimental results showed a potential gain of up to 10 urad half-crossing by powering both wires embedded in the jaws of TCTPV.4R1.B2 and TCTPH.4R5.B2 at maximum wire current (350x2 A per wire collimator), at nominal TCT opening and using 3 nominal beam trains.

The motivation of the proposed intervention is to prove the wire collimators BBLR compensation also for B1 as well as to gain operational experience with wires during the operation in Run 3 and prove potential for HL-LHC.

The proposed intervention consists in: