Anti-solenoid status and outlook

A. Gaddi, A. Bartalesi, M. Modena

Anti-solenoid

Introduction

The study of the magnetic design of the detector forward region, that includes the QD0 and the anti-solenoid, has started last summer as a collaboration between PH, TE and BE Departments with the aim of developing the conceptual design of a “real” QDO & anti-solenoid, taking into account their environment.

PH has given the boundary conditions and the integration constraints of the Machine-Detector Integration region, TE has performed the magnetic and mechanical calculations, BE has made the evaluation of the MDI magnetic design on the beam dynamics.

We present here the work done and the results obtained on the conceptual design of the anti-solenoid.

First Ansys model for forces & stresses

The first calculations done during this summer were performed with Ansys, on a simplified model of three lumped coils. Two load cases have been calculated, mainly to evaluate forces on the anti-solenoid:1) both the detector solenoid and the anti-solenoids are energized2) only the anti-solenoids are energizedLoad case 1

Load case 2

Model with fancy current distribution

A second, more refined, model has been realized to optimize the number and position of the coils of the Anti-solenoid. This new model has been done with Opera s/w and it gave much better results, but it was not compatible with the actual design of the detector forward region (interference with the QD0 support tube).

Latest model with 6 coils + Fe disk

A third model has been done with Opera s/w, schematically representedhere, with 6 coils plus a ferromagnetic disc inserted just in front of QD0.

Low current superconducting coils12 – 0.1 – 3.5 – 15 – 28 A/mm2

Improved shape winding 80 A/mm2

Ferromagnetic disc (Permenorm 5000 s4)

Bz and Br field profile along beam line

Outlook and conclusionConclusion of the conceptual design phase.

Magnetic design: the results of several simulations done withOpera show that the actual design of the anti-solenoid is effectivein both protecting the QD0 and preventing beam distortion at IP.The smoothing of a narrow Br peak just in front of QD0 shall beaddressed.Mechanics: the forces the anti-solenoid has to withstand arehuge. How to keep them would be a challenging task.

Collaboration with other projects (2e & Comet) and look back atother recent magnets (BESS, Wasa, …). Many mid-size thin coils havebeen built or designed in the past. From an accurate look to theseprojects we could take good ideas for our design.

Towards the engineering phase. A tight collaboration between PHAnd TE is convenient also for the engineering phase. TE colleaguesmay have more experience in such kind of magnets, but PH shallkeep an overall view of what is going on in the detector forward region.