Minutes of the CPT meeting on May 1st, written by Adi - Laser still with customs, more forms being filled, arrival in a couple of days hopefully. - 100 LYSO plates delivered. -> Mail send to Renyuan to ask if he can do the light yield measurement as for the Shashlik tiles. Likely not crucial for us, but would mesh well with the main Shashlik effort. I also asked Renyuan if he can provide us four short WLS fibers to read out the tiles. (Adi) - Discussed with Shashlik people to get a loan of 30 W plates and Tyvek sheets. Purchasing (Adi) our own W plates would be "expensive" - though exact cost not know. - Two additional DRS4 ordered to get initially intended three pieces. (Cristian) - Cristian sent the link to the updates list of misc. items : https://www.dropbox.com/s/020dwsibwytdxjy/buy_list.xlsx Of particular importance is a consistent set of proper cables for the next test beam and beyond since they were found to have a rather big impact on the quality of the data. --------------------------- Hardware assembly : Next step is a LYSO plate / Pilas test assembly. I uploaded some improved slides to INDICO : https://indico.cern.ch/event/316769/ with some suggestions as to how to proceed. Look into doing it ourselves (Dustin, ...) Optimistically, have this ready for May test beam. -------------------- Discussion on May test beam : Objectives are : -Disentangle exact impact of pin hole on the measurements we performed in March. - Reproduce results from March with signals which are guaranteed from scintillation light and which are correlated with the energy measurement. - The above with a reduced set of configurations. Proposal : Just longitudinal and transverse setup with the 20 cm LYSO xtal. - If ready and above measurements understood : LYSO plate assembly. Preparations : - Perform laser measurements on bare MCP, LYSO xtal and possbly quarz bar with PiLas pusles at FNAL and with and without pin hole. Goal is to quantify impact of pin hole (tail cutting, signal amplitude reduction) (Si and Artur). Note : Only evidence we have all seen so far is scope traces with PMT and pin hole (see attached plot). Anecdotal evidence that this was reproduced with laser at FNAL (laptop data, to be reproduced with test above). Since all is available at FNAL and laser and laser setup at CIT not yet ready to use, doing it at FNAL is probably faster. - Get misc items (in particular cables) and if possible LYSO plate assembly. => Additional suggestion : Machine some cubes of lead or brass to fit around the LYSO xtal to shield far side MCP from shower particles to ensure that there are no accidental hits. See slide 6 of the LYSO plate assembly slides above. If we machine this from eg. thick plates of lead or brass we could stack it as needed, up to 20 cm thick in the longitudinal setup, leaving a narrow gap in the transverse setup. The discussion of the above items repeatedly brought us back to the issue of what exactly the impact of the pin hole and if the signals from the crystal in the march test beam are from scintillation, cherenkov or direct hits of the MCPs attached to the xtal. In this context we discussed the next tow items : ------------------------------ Standalone simulation (Artur and Si, see slides at https://indico.cern.ch/event/316769/) Important observations: Slides 4&5 : Pinhole greatly reduces the amount of photons detected (trivial), arrival time spectrum has narrow peak of cherenkov photons (not trivial, may suggest that we see cherenkov light in the March TB). Note however that the scintillation light signal needs to be scaled up by 60 to reproduce actual LYSO LY. Then the plot will not exhibit the cherenkov peak any more. => make plot with scaling scintillation light by 60, with extended y scale to show full pulse. Also, photo efficiency will reduce cherenkov light due to large wavelength spread. Slide 9 : Photon simulated entering from one side shows large difference in detected signal the end of the xtal. Would match observation in the TB. => need equivalent plot without hole and with large reflectivity. These plots would match the envisioned laser tests described above. Slides 10 ff : Time evolution shows reflected waves of photons inside the xtal. We have argued that this may cause the peaky pulse structure observed with eg. the MCPs. See also page 5 which has one such peak. Time between initial and reflected peak is 750 ps. Some additional plots were shown which are not in the slides. In particular a plot which seem to suggest that the pin hole has no effect on the time spectrum of the pulse. => ARTUR, PEASE ADD THESE PLOTS TO THE SLIDES. In summary, the simulations are very valuable. Some results seem to confirm the TB observations (amplitude ratio near side vs far side), others do not match TB observations (tail cutting of pin hole). However, the latter is not proven to actually occur in a consistent way. laser tests to shed light, beam test without pin hole to confirm. ----------------- Longitudinal analysis (Cristian, see slides) : Energy spectra and time differentials of longitudinal setup for protons, electrons of different energies. Energy spectra of protons rather similar between all four MCPs. For electrons, far side spectrum significantly lower. -> Speculation that this is because we are dominated by direct hits and close to the pin hole light (cherenkov of scintillation) and not by full shower light. Run 66 is actually 16 GeV electrons. Apparently differences between spectra of different runs. Time differentials are all rather similar, regardless which pair of MCPs is compared. The mean of the time differentials on the top left plot changes between protons and electrons. May be indication that the electron signal in the near side MCP is NOT direct hit dominated. -> CRISTIAN, ADD PROPER LABELS TO THE PLOTS, IN THREE DAYS NOBODY REMEMBERS WHAT THEY SHOW. ------------------------------ Conferences : Elba (May 28) : Abstract submitted, decision pending. As TIPP. TIPP (Artur) : As Calor, but backed up by simulation and pin hole checked with laser tests + more detailed analysis. If lucky, some results from May TB. NPID (July, Tours) : Poster, to to be decided. IEEE (Cristian, October) : NEED abstract and summary (use TIPP abstract, add more detail on setup (crystal, readout, sensor) and indicate results. May TB results, more laser OTTJ measurements, possibly range of photo sensors, LYSO and LYSO/W stack measurements (laser and beam (July ?)). Anatoly considering going with Anatoly tests and possibly interested in Hamamatsu evaluation. --------------------------------------------- Cheers, Adi