Hello Michele! Thanks for your answer!... Answering your questions we have a collimating mirror upstream the mono and the water temperature used to keep this guy cooled is within +/-0.3°C. Regarding fluctuation in the water flow, I dont know, maybe not cause we have a dedicated thermal bath with fixed pumping speed Let me ask you a few things: - Do you remember why you decided to keep the 1st crystal at 8ºC instead of some point nearer of room temperature? Recently we changed from around 10ºC to 40ºC in order equalize temperature inside the mono (motors average temperature was 40°C). - What kind of system do you have to tune the crystals? - How do you usually do long energy measurements? Scanning theta, absorption edge ? - What kind of BPM do you have installed? Are they reliable? Be sure MX2 is already very popular with the neighborhood! : ) Thanks for the help one more time and regards, Lucas. -----Mensagem original----- De: Michele Cianci [mailto:[EMAIL PROTECTED] Enviada em: segunda-feira, 28 de julho de 2008 04:26 Para: [EMAIL PROTECTED] Assunto: Re: [ccp4bb] Beamline Stability Issues Hi,
I commissioned and made operational MAD 10 at Daresbury. The machine was operating at 2 GeV with 200 mA routinely and our beamline was on a 2.4T wiggler. in front of the mono we had a cooled collimating mirror that would take most of the heat out. then the mono had the first crystal cooled to 8 degrees. The second crystal was not cooled and it was saggital for horiz. focussing. With that set up we could see drifts only below 5500 eV. they would appear as an intensity drift of 50% over 30 minutes when changing from higher to low energies. It would disappear when returning to higher energies and half an hour of rest. We had other drifts related to the machine this time, but they had not correlation with the energy set at the mono. they would appear at any energy and usually after a shut-down or certainly first thing in the morning. These could be solved by asking for a re-steering of the machine (that makes you very popular with your neighborhood!!). To isolate the problem find an high energy at which you are sure about performances and then do what you can to identify the contribution from the machine. When you are sure about the machine then change energy and see what happens. Take one step at time. Do you have some optics in front of your mono? Are they cooled? are there fluctuations in the water flow? hope this helps, have fun, mkl Michele Cianci, Ph.D. EMBL Hamburg Outstation Building 25a c/o DESY Notkestrasse 85, 22603 Hamburg - Germany Tel. +49 (0) 40 899 02 118 Fax. +49 (0) 40 899 02 147 e-mail: [EMAIL PROTECTED] ------------------------------------------------------------------- My page: http://www-db.embl.de/jss/EmblGroupsHH/per_4431.html ------------------------------------------------------------------- Petra-III page: http://www.embl-hamburg.de/services/petra/ ----- Messaggio originale ----- Da: Lucas Sanfelici <[EMAIL PROTECTED]> A: CCP4BB@JISCMAIL.AC.UK Inviato: Venerdì 25 luglio 2008, 16:19:29 Oggetto: [ccp4bb] Beamline Stability Issues Hello all! Does someone have experience in minimize energy instabilities in beamlines? MX2, our new beamline devoted to MX experiments, are facing problems with energy drifts. As far as we could notice, theses drifts are results of the contribution from several sources - possibly electron beam movements, heating of optical elements, etc... LNLS is a 2nd generation machine with 4 straight sections available for insertion devices. MX2 is a 2T wiggler-based beamline and produces a peak flux of 10^11 photons/s. What I'd like to know, before start performing calculations, how far should I expect the heating of a non-cooled 2nd crystal affects energy? Does someone know cases of a few eVs drifts? Thanks in advance and regards, Lucas Sanfelici Physicist Brazilian Synchrotron Ligth Source- LNLS (www.lnls.br) Diagnostics Group PO Box 6192 Postal Code 13083-970 Campinas-SP Brazil Phone: +55-19-3512-1153/1152 Fax: +55-19-3512-1006 E-mail: [EMAIL PROTECTED] _____ Posta, news, sport, oroscopo: tutto in una sola pagina Crea l'home page che piace a te! <http://us.rd.yahoo.com/mailuk/taglines/isp/control/*http:/us.rd..yahoo. com/evt=52437/*http:/www.yahoo.it/latuapagina> .
