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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]> > To: [log in to unmask], [log in to unmask], > [log in to unmask], [log in to unmask], > [log in to unmask], [log in to unmask], [log in to unmask], > [log in to unmask], [log in to unmask], > [log in to unmask], [log in to unmask], [log in to unmask], > [log in to unmask], [log in to unmask], > [log in to unmask], [log in to unmask], [log in to unmask], > [log in to unmask], [log in to unmask], [log in to unmask], > [log in to unmask], [log in to unmask], > [log in to unmask], [log in to unmask], [log in to unmask], > [log in to unmask], [log in to unmask], > [log in to unmask], [log in to unmask], [log in to unmask], > [log in to unmask], [log in to unmask], > [log in to unmask], [log in to unmask], [log in to unmask], > [log in to unmask], [log in to unmask], [log in to unmask], > [log in to unmask], [log in to unmask], > [log in to unmask], [log in to unmask] > Cc: [log in to unmask] > 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 >