Summary of E835 Tuesday Meeting 3/21/2000 Present: Gollwitzer, Robutti, Negrini, Legger, Garzoglio, Luppi, Graham, Seo, Borreani, Obertino, Stancari (M), Stancari (G), Boca, Kasper. (Items are not necessarily in the order of the meeting) Pbar Status: We know nothing more than the last message Elvin sent out yesterday. Stephen/Keith will get an update tomorrow. Stephen does not expect to be running before a week from now. All Experimenters' Meeting on Monday: Stephen showed a transparency with the 4 points of last weeks stack on a plot showing the January scan as well. The new points fit reasonably well on the curve of the January scan. Stephen had shown the data as evidence that we had done something with the beam provided. (Added for the minutes). Ralph Pasquinelli asked at the end of the AEM what would be done about the fact that 835 had lost 2 weeks of prime data time. There was an awkward silence in the room till the Director answered that this was too recent to have a developed reaction. DAQ: Keith repeated his request for feedback on the proposal to make the ADC pedestal on the Sci-Fi to be pedestal plus 4 times the rms of the pedestal. Keith showed a distribution of the Sci-Fi pedestal rms's; this peaks around 7 counts and extends to about 12 (at the base). The fraction of times there is a hit in the random gate events above 2 x rms, the current cut, is 10% - much larger than a gaussian distribution would predict. A typical MIP peak is at 400 ADC counts. Paolo and Wander have not been able to reproduce the DAQ failures of the run since the Sci-Fi have been worked on. (see Sci-Fi later). Michelle said she was writing an end-of-stack script that would spool various files to tape, move various files to the appropriate machines at the end of a stack and generally do house-cleaning and sorting. Stephen asked that she distribute a design note. Keith and Michelle warned that there would have to be some intelligent operator to run the program - to deal for example with runs whose tapes were overwritten (eg runs with something wrong found early) but whose diskfiles still existed. Energy Calculation and last week's scan: Eleonora showed a new version of the psi' scan plot where the new points seemed to lie even better with the January scan. She now has the final version of the energy calculation for these points from Gabriele. The psi' mass comes out fine but the width is 0.4 MeV (cf 0.3 MeV in E760). Stephen asked if the plot could be put on the web - see later email from SP. Gabriele explained the evolution of the energy calculation. There are now two frequency spectra of the beam - one with 1.7kHz bandwidth and one with 30 kHz bandwidth. The one with 30 kHz is/will be used to see the tails of the beam distribution while the 1.7kHz one gives the central distribution. The means of the two distributions differ by quite a lot (number should be given but I don't have it) which Giulio attributes to background and binning effects in the broad distribution. Till we understand how to use the broad span, we will stick to the standard one. In response to a request from Michelle for publication of the energies, Gabriele replied that he is getting all the infrastructure together to do so. He will put the current energies somewhere. Phi-Phi filter. GianLuigi reported that he was working on the Monte Carlo program to help develop/test the phi-phi filter. Enrico commented that Maurizio (Lovetere) had found that a problem with the (simulation of the) behavior of hadrons in the CCAL was associated with some short-cut made to save time. GianLuigi said he thought the current MC was fine except for the translation from energy to adc counts. There was some further private discussion on this. Sci-Fi: Eleonora reported that Wander had worked on the Sci-Fi electronics. He has reduced the low voltage on one cassette and since then has seen no oscillations, fluctuations or other misbehaviors. Wander and Matteo have also been fixing some channel assignment stuff in the online-monitor/offline. Straws: Margherita reported that T0's have been calculated by Nadia/Flavio and some data on efficiencies and resolution will be distributed. Giovanni showed the hit-map distribution which does not look too bad now - some hot channels and regions but generally smooth.The audible alarm on HV trip has been successfully re-implemented on the Ezio/Flavio beeper module and a written procedure on what to do if it sounds is being produced. Work is going on to get the temperature readout implemented. In answer to a suggestion last week from Stephen that we widen the straw pulses to the TDC's to reduce the number of hits, Giovanni explained that he had been told that this could only be done by changing capacitors in the drivers in the pit. Stephen withdraws suggestion. CCAL: The bad slot has not been addressed. FCAL: Seon-Hee showed some laser data. Stephen: YES WE WILL HAVE TWO OF THESE MEETINGS A WEEK FOR NOW.