SLAWG #15 ZS fiducialisation and alignment today B. Balhan 08/03/2017

Outline ZS individual tank alignment in laboratory SPS alignment LSS2 Girder Alignment ZS wire Alignment accuracy Final alignment using beam How to improve 08/03/2017 Slawg#15

ZS individual alignment in laboratory In order to avoid alignment process in the SPS, all ZS are aligned in the lab using a “ ZS alignment jig” to copy all references Alignment sequence: Install ZS model on alignment banc with correct levelling (tilts) Setup optical measurement system In vertical and radial position (ZS wires, Alignment Target) Replace ZS model by ZS to align Mechanically adjust tilts, upstream and downstream wires and alignment targets. Set cathode positioning Set 0 anode positions Using this method, all ZS are identically aligned and “Plug and Play” ZS are placed on 3 spherical Feet, keeping the positioning. 08/03/2017 Slawg#15

SPS alignment LSS2 Since all ZS are identical, once the girder feet are correctly aligned, ZS can be removed and replaced without need for an alignment campaign in the ring. Tunnel alignment sequence: The girder is placed in nominal position Quadrupoles (216-217) targets are used as references. Tilts are checked and adjusted if required (radial & longitudinal). Vertical and Radial positions are checked and adjusted if required. 08/03/2017 Slawg#15

Girder Alignment. During re-cabling campaign (irradiated cables replacement, last one in 2009),the girder levelling is fully checked, ZS and pumping modules feet are as well adjusted using “ZS alignment jig” or non radioactive tanks. Upstream & Downstream Girder adjustment 08/03/2017 Slawg#15

ZS wire alignment accuracy In order to reduce the tilt effect on the wire position, The Anode shaft can be used to know exact upstream & downstream wire positioning (initial laboratory measurement required). Initially designed to improve alignment, but not used since at least 30 years. 08/03/2017 Slawg#15

ZS wire alignment using beam The Final alignment is done using the beam, few times a year… 08/03/2017 Slawg#15

How to improve During scans, the limitation factor is the accuracy of 0.1 mm of the anode motorisations displacements (bigger than the wires width 60µm & 100µm) The actual Anode motorisation seems to be more accurate (at least 0.05 mm) An estimation has been done by Ch.Boucly to improve acquisition and control of these displacements ~ 100 kCHF, New cabling required New control (Software/Hardware), DAC/ADC 16 bit Use motorisation in servo instead positioning ? Test to be scheduled in 867 to validate the estimated accuracy. 08/03/2017 Slawg#15