Present: E. Adli, J. List, B. List, K. Yokoya, L. Kennedy, R. Tomas

Topic: Follow up on spin transport and polarisation preservation in LCF.

The minutes from last meeting were gone through, in order to get everyone on the same page. 

Spin/polarisation studies:

The spin rotation design needed for a double BDS, with different X-angles, is a topic quite distinct from BDS studies, and can be done by different teams.

In addition to the design of a system capable of changing the spin rotation on a pulse to pulse basis, general polarisation studies should perhaps be revisited.  E.g. linac tolerances for polarisation preservation. Jenny: a thesis was made on overall spin studies for ILC a few years ago, not very detailed.

Post collision line:

Only basics studies done for CLIC, at the CDR time, for3 TeV.  Considered challenging for highly disrupted 3 TeV beam. 

Design and lattice exists for ILC 500.  To be adapted to LCF380. 

Polarimetry measurements:

Polarimetry measurements need to be re-visited?  Compatibility with CLIC-like BDS?

Some literature from the past ;), but maybe useful:

• - JINST paper on ILC BDS spin tracking & polarimetry https://inspirehep.net/literature/1295488
• - PhD thesis M.Beckmann, ``Spin transport at the ILC and its impact on the measurement of polarisation,’’ https://inspirehep.net/literature/1276876
• - proceedings on impact of ground-motion on depolarisation: https://inspirehep.net/literature/925967

L-star: ILC detector can work with short L*, ~4m.  To be discussed before taking final decision   

In the coming month or so, we need to organise the work, together with the CERN Study Coordinator :

- prepare a task list

- define who will do what

- define LCF380 lattice home and ownership

- timeline is extremely short (report ready by Dec 2027, ink. civil engineering)

Important to involve external institutes, profit from university students.