Dear Ron,
I'll be happy to take part in this special effort, since the
presence of TWO highly polarizable beams is one of the principal
attractions of the e-e- version.
Let me know how we proceed. I'm spending the next months in Aachen
- but since we'll meet next week inSitges, communication should be easy.
Regards,
Clem.
On Wed, 14 Apr 1999, Ron Settles wrote:
> Date: Wed, 14 Apr 1999 19:00:50 +0200
> From: Ron Settles <[log in to unmask]>
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> Subject: Polarisation at the LC
>
> Dear Friends,
>
> Several people have expressed the wish to gather
> the material for the polarisation program at the linear collider
> into a document containing the physics, experiment and accelerator
> issues. At our last meeting in Oxford, the Ecfa/Desy OC agreed
> that I have a go at getting a small group of us together to write
> this up so that we have all of the information in one place.
> Of course it should not be limited to the Ecfa/Desy study for
> obvious reasons since there is probably activity in the American
> and Asian studies. Herb Steiner/LBL has been saying for a while
> we should do this (see his mail below), and independent of
> that Eilam Gross/Weizmann and Peter Zerwas/Desy expressed interest
> at the Ecfa/Desy Oxford meeting, so that would make 4 of us
> in such a working group for the moment.
> Polarisation is of course a powerful tool in e+e-,
> as the SLC/SLD example is showing us, and at the LC it will
> be even moreso. Each of the physics groups has polarisation on its
> agenda, so a lot of information is out there but scattered for now.
> But there is nitty gritty hardware which has to be understood
> before any physics with polarisation gets done (Herb's note
> below raises other points), and this has to be put in perspective
> with other big jobs like building the accelerator or the detector.
> Since manpower and money is involved, the hardware needed for
> polarisation must be part of the proposal for the machine and for the
> detector.
> Because of SLC, e- polarisation is assured and essential
> for many of the physics-with-polarisation experiments (in the end
> there might be a scheduling problem, which would be a nice situation
> to be in, but let's not worry about that now).
> However e+ polarisation is less straightforward.
> At Hawaii LCWS93 there was some discussion, and its usefulness was addressed
> in our workshop series in 1995 and at Claudio Verzegnassi's workshop in
> Lecce 1996 (and probably on several other occasions). Increasing statistics,
> increasing the effective polarisation and measuring the degree of
> polarisation (the Blondel scheme) were some of the arguments for e+
> polarisation. Since a major hardware R&D program is needed
> to make e+ polarisation possible, it was not clear if those reasons
> were good enough. Recently at the Ecfa/Desy Oxford meeting, more potent
> reasons appeared, and the physics groups should continue to think about this.
> On the hardware side there are schemes on paper (JLC showed a source
> at LC95 and TESLA has a design for a helical undulator DESY/TESLA 96-05),
> but I don't know whether any real hardware prototypes are being built.
> If you are interested in joining a LC polarisation wg,
> please let me know.
> Be seeing you at Sitges or elsewhere...
> Ron
>
> P.S. I've cludged the Slac LC mailing list and the European one
> together for this mail, so apologies if you get this twice.
>
> -----------------------------------------------------------------
>
> From: SMTP%"[log in to unmask]" 29-OCT-1998 20:21:39.09
> To: SMTP%"[log in to unmask]"
> CC:
> Subj: Re: LC Detector Sessions at Frascati Meeting 7-10 Nov.98
> 29-OCT-98
>
> DEAR RON:
>
> I WAS SORRY TO HAVE MISSED YOU DURING YOUR SHORT VISIT TO LBL RECENTLY.
> I WANTED TO ASK YOU WHAT IS BEING DONE ABOUT POLARIZATION-RELATED ISSUES
> IN YOUR STUDIES. IT SEEMS TO ME THAT EXPERIMENTS WITH POLARIZED BEAMS
> WILL PLAY AN IMPORTANT ROLE IN ANY LINEAR-COLLIDER RESEARCH PROGRAM,
> AND TO THAT END I THINK IT IS DESIRABLE TO INCLUDE THIS OPTION IN YOUR
> PLANNING. I AM THINKING HERE OF PHYSICS-RELATED ISSUES, ACCELERATOR-RELATED
> ISSUES, DETECTOR-RELATED ISSUES, AND ISSUES ASSOCIATED WITH TECHNOLOGICAL
> IMPLIMENTATION. I AM SURE THAT YOU AND YOUR COLLEAGUES ARE WELL AWARE OF
> THE ROLE OF POLARIZATION, BUT I HAVE NOT SEEN MUCH REFERENCE TO IT IN YOUR
> VARIOUS STUDY DOCUMENTS. SOME OF THE TOPICS THAT COME TO MIND ARE POLARIZED
> ELECTRON (POSITRON) SOURCES, POLARIZATION DILUTION AND DEPOLARIZATION EFFECTS,
> POLARIMETRY (WHERE AND HOW), NEEDED ACCURACY (RELATIVE AND ABSOLUTE), ENERGY
> CALIBRATION, COMPATIBILTY WITH ACCELERATOR/DETECTOR DESIGN AND OPERATION,
> POLARIZATION ROTATORS, ETC.. IF YOU HAVE NOT ALREADY DONE SO, IT MIGHT MAKE
> SENSE TO SET UP A WORKING GROUP OF INTERESTED PERSONS TO COME UP WITH A
> DETAILED PLAN TO ADDRESS THESE ISSUES, TO MAKE SURE THAT THE ACCELERATOR AND
> DETECTOR DESIGN TEAMS ARE WELL AWARE OF THE PERTINENT ISSUES, AND THEN TO
> INTEGRATE THE RELEVANT PORTIONS IN YOUR DESIGN REPORTS. I THINK THERE ARE
> HIGHLY QUALIFIED PHYSICISTS IN YOUR PART OF THE WORLD WHO COULD UNDERTAKE
> THIS TASK VERY EFFECTIVELY.
>
> BEST REGARDS,
>
> HERB
>
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