MINUTES OF THE 12th DEAR COLLABORATION MEETING (11-12/02/2002) Participants: M. Bragadireanu M. Cargnelli G. Corradi C. Curceanu (Petrascu) J.-P. Egger C. Guaraldo M. Iliescu T. Ishiwatari K. Itahashi M. Iwasaki V. Lucherini F. Lucibello L. Ludhova F. Mulhauser R. Petrascu L. Schaller D. Sirghi F. Sirghi J. Zmeskal 1) STATE OF THE EXPERIMENT AND OF MACHINE (C. Guaraldo) The state of the experiment was reviewed: - The capability of creating and detecting exotic atoms at DAFNE with the DEAR setup was demonstrated in the May-June 2001 runs, by the measurement of two previously unmeasured transitions of kaonic nitrogen. - A completely new setup was built and tested in the DEAR lab; - A new target, only-kapton made, was built and tested during the December run; - A new detection system was built, containing: - 16 CCD-55; - a new readout electronics, based on commercial NI boards; - a new preamplifier, giving excellent performances in terms of linearity and stability; - A full filtering of the power supply in the pit was realized; - The ground connections were redesigned in the pit. The state of the machine was presented at point 2a. The three Milestones requested by the LNF Scientific Committee, asking definite answers in the April (*) session, were recalled; this argument was subject of the point 7 in the Agenda. 2) RESULTS OF THE ENGINEERING RUN OF DECEMBER 2001 2a) Machine (C. Guaraldo, C. Curceanu (Petrascu)) --------------------------------------------- The following arguments were presented: i) what has been done; ii) what has not been done; iii) where we are and how far we can go. i) for the first time, in the December engeneering runs a low-beta optics was tried, with positive exit, for DEAR. A detailed description of DAFNE - relevant parameters, beam dynamics, operation, limits and perspectives - was presented. All this material will be included in a Technical Note in preparation. Due to problems to an RF cavity it was not possible to inject currents higher than 450 mA; however, the luminosity was a factor 2 - for same currents - higher in December with respect to May-June runs. ii) The machine was not operated in order to reduce background; the new scrapers were installed in January and their effect will be firstly checked by KLOE in February and then by DEAR in March runs (*). New octupoles were as well installed and an increase in the luminosity is awaited. iii) It was shown how the increase in the efficiency of collisions, by the use of the new optics, extrapolated towards higher currents, and by adjusting the data acquisition time, can allow to DEAR to collect about 1 pb**-1/day. Details can be found in the DEAR Technical Notes IR-38 and IR-40. 2b) New target cell (C. Curceanu (Petrascu)) ---------------------------------------- The results of the engineering run performed in December 2001 were presented. The x-ray spectrum obtained with the CCDs-05 (5 and 6) was shown, where all data were added up - in order to increase the statistics. It was shown that no line is present in the spectrum, apart of aluminium, silicon, calcium (coming from the epoxy-fiber supports) and zirconium (calibration foil). Particulary, NO IRON was present in the spectrum. Moreover, a comparative analysis of the December and May-June spectra showed that, by subtracting the December spectrum from the May-June one, no nikel is present. Details of the analysis are reported in the DEAR Technical Note IR-39. 2c) Background studies (C. Curceanu (Petrascu), D. Sirghi, T. Ishiwatari) -------------------------------------------------------------------- The results of a series of tests of different shielding and setup configurations, performed during the December engineering runs, were shown. The use of the tungsten 300 microns foils as degrader turned out in no reduction of the background; the lateral lead shielding was checked to be fundamental in background reduction. Details and more results are presented in the DEAR Technical Note IR-41. The results of Japanese analysis were as well shown; the energy distribution of 1 to 6 clusters size were shown to present the m.i.p.s contribution for the CCD-05; accordingly, the energy spectrum of 1 single pixel has a contribution coming from the m.i.p.s at an energy peaked at about 8 keV. 2d) Emulsion studies (K. Itahashi) ------------------------------ The results of the emulsion studies performed during the December runs were shown. Four emulsions were carefully analysed to search for background sources; it was shown that background, as expected, is mainly represented by charged (electrons) particles with energies, in principle, higher than 1 MeV; their distribution is scaling with the square of the distance. It was not possible however to distinguish the effect of "normal" background by the effect of the background during injection. Further studies are eventually to be planned and performed. 3) STATUS REPORT ON THE KAON MONITOR (M. Bragadireanu, V. Lucherini) Kaon monitor proved to be a very efficient instrument to measure the luminosity delivered by DAFNE in the DEAR IP. The method of deriving the luminosity was briefly recalled. The results of the kaon monitor data acquisition were presented. Both information, in time (TDC) and in energy deposited (ADC) were carefully analysed, and various correlations studied. The possibility of using the information delivered by kaon monitor to perform studies of kaon scattering on carbon-nuclei in the DEAR pipe was taken into consideration. 4) THE NEW CRYOGENIC SETUP FOR KAONIC HYDROGEN: DESCRIPTION 4a) Cryogenics (J. Zmeskal) ----------------------- A completely new cryogenic setup - vacuum jacket and target cell - was designed, built and tested. The new setup fulfills the following goals: - has as less material as possible in front of the CCDs; - has an improved shielding, all external to the vacuum chamber; - has an easier access to the CCDs and target. The new target cell was built in 50 (75) microns of kapton, with epoxy-fiberglass reinforcement. 4b) Readout electronics (M. Iliescu) -------------------------------- A new electronics was built, based on commercial NI boards. The new electronics is much more flexible and performant than the "old" one. Objectives and realization: - increase eight times the full capacity of the setup in order to use 16 CCD55; - simplify the maintanance by reducing the amount of artisanal electronics; - increase the flexibility in adjusting the CCD readout parameters; - increase the quality of readout: - improve the output signal integration; - reduce the pickup noise The full system is operational in the DEAR laboratory. The first tests, performed with CCD-55, gave excellent results in terms of resolution (136 eV FWHM at Mn line) and stability, as well as thermal noise. 4c) Preamplifier (G. Corradi) ------------------------- The block diagram of the new preamplifier was presented. 8+1 new preamplifiers were built and tested. The new preamplifier has excellent characteristics: an amplification factor of about 270, with linearity better than 1:10000 on the whole dynamical range. 4d) Slow monitor status report (M. Bragadireanu) -------------------------------------------- The status report of slow controls was presented. The system worked very well during the 2001 runs. Features to be still implemented are: - monitor leak for hydrogen; - the 4-wire configuration for the target temperature measurement; - shielded cabling to avoid noise pick-up. By the software point of view, the following items were realized: - new version with modified user interface; - alarm for each monitored parameter; - user priviledges. 5) NEW SETUP FOR KAONIC HYDROGEN: PERFORMANCE IN LABORATORY TESTS 5a) Cryogenics (J. Zmeskal) ----------------------- Concerning the target, the following tests were performed: - cooling tests and under pressure tests: 1 day at 25 K at 3 bars; 4 days at 25 K at 2.5 bars. All the previous tests were performed with the 50 microns target; in the future two new targets, 75 microns thickness, will be built - more safe to be operated. 5b) Linearity (C. Curceanu (Petrascu), M. Iliescu) ---------------------------------------------- The results of a linearity test for the new detection system (new electronics, new preamplifiers and new CCD-55), performed in the DEAR lab, were shown. Different materials were excited and the emitted X rays registred by CCDs. The signals (Ti, alpha and beta lines; Mn, alpha and beta lines; Rubidium, alpha and beta lines; Mo alpha line) were checked for the linearity test: energy as a function of channel. The new detection system proved to be linear within about 1-2 eV in the region of 6 keV, which represents, in fact, the lower limit of the electronics performance (preamplifier in particular). Details of the analysis are presented in the DEAR Technical Note IR-42. 5c) Resolution (C. Curceanu (Petrascu), M. Iliescu) ----------------------------------------------- The data collected during the linearity test were used in order to perform an analysis of the resolution as function of energy. The resolution of the different x-ray signals (see 5b)) were analysed as function of energies. It was shown that it is not possible to fit the resolution, as function of energy, by using the "simple Fano" formula; in fact the presence of a term quadratic in energy seems to be requested to have a good fit (a good chi**2/NDOF). Details can be found in a Technical Note in preparation. 6) MONTE CARLO SIMULATION FOR THE NEW SETUP (C. Curceanu (Petrascu), M. Cargnelli). The results of a Monte Carlo study of the new setup with the target filled with various gases were presented. It was shown that for kaonic nitrogen at a density of about 5 equivalent NTP density the expected signal is about 1800 X rays detected/pb**-1. The signal of kaonic helium for an yield of about 10% (to be checked) and a density of 10 equivalent NTP density is about 130 X rays detected/pb**-1. For kaonic hydrogen, with an yield of 3% and a density of about 40 equivalent NTP density, the signal is about 130 X rays detected /pb**-1. Details on kaon-stopping distributions and momenta were as well shown, together with an analysis of the stopping point distribution as a function of DEAR carbon fiber pipe thickness with its error. The Monte Carlo simulation results performed in Frascati and Vienna were shown to give the same results. 7) MILESTONES REQUESTED BY THE LNF SCIENTIFIC COMMITTEE, TO RECEIVE ANSWERS IN THE 16-17 APRIL SESSION. 7a). "In the test run the collaboration should repeat the nitrogen measurement, or substitute it with a measurement in helium, showing that they are able to see the new lines with a better, or at least equivalent, quality". It was decided that the measurement in March run (*) will start with kaonic nitrogen - which gives the highest signal to be detected. The new setup will measure the new "point zero" for background; the effect of the new scrapers will be performed as well. Studies of the background dependence as a function of the geometry of the hole in the platform will be performed as primary task. 7b) "Guarantee a safe operation of the hydrogen target" (J. Zmeskal) In the presence of Dr. Bertolucci, the new LNF Director, the way in which DEAR operates the hydrogen target was presented, clearly showing which are the safety features in dealing with hydrogen. A Note will be specifically written on this item (safety procedures) and given to the responsible of Safety Division of the Laboratories. 7c) "The results of the test run should show that the machine and experiment conditions are such to allow a measurement at the level of 7% in time of two-three months" (C. Curceanu (Petrascu), M. Cargnelli) The results of a simulation of precisions in shift and width, as a function of S/B ratio and number of collected signal events were presented. It was shown that, with a conservative yield of 1.5% for the kaonic hydrogen transition and with a S/B ratio of 1/10, a precision of 7% in the shift can be reached with an integrated luminosity of about 40 pb**-1. A similar result (11 % in precision) was obtained starting with the background measured in May-June run of last year, on which the signal of kaonic hydrogen was simulated, for a S/B ratio of about 1:40 and an integrated luminosity of about 60 pb**-1. 8) ORGANIZATIVE ASPECTS OF THE 4-WEEK RUNS IN MARCH (C. Curceanu (Petrascu)) The runs to be performed in March are VERY IMPORTANT - see point 7) of Agenda. There will be many shifts (90) and many tasks to be fulfilled: - data acquisition; - data processing; - data analysis; - any other work necessary while running. In order to fulfill at best the tasks and present the results to the Scientific Committee the presence of all groups is required. The booking of guesthouse should then be done in due time. For the March run the participation of groups, apart of the LNF one, tentatively is the following: - Jean-Pierre: as much as possible; - from Vienna: 2-3 persons; - From Japan: Tomo and eventually Kenta; - from Fribourg: Livia for 10 days; - from Bucharest: 1 person. 9) PRELIMINARY ORGANIZATION OF THE JUNE, JULY (AUGUST) RUNS (C. Curceanu (Petrascu)) For the long period of data taking previewed for summer all arguments presented at point 8) are twice valid. The presence of external groups, tentatively, is: - from Vienna: 2-3 persons; - from Bucharest: 1-2 persons; - Jean-Pierre: as long as he can; - Japan and Fribourg will give an answer in due time, compatible with the other tasks they have. 10) FIRST DISCUSSION ON THE "KAON MASS PAPER" (J.-P. Egger, C. Guaraldo) An exhaustive discussion was held concerning the "kaon mass" paper, considering also the observations received by mail. Many points were touched and discussed: from the scientific part to the experimental setup one. All the observations were collected and will be considered for the second version of the paper which will be soon distributed to the Collaboration. The list of authors was discussed and approved. 11) CONFERENCES 2002 (C. Guaraldo) The list of talks assigned to DEAR is not yet completed. For the moment, in MESON 2002 (Cracow) - M. Iliescu will present the results so far obtained and the future plans. 12) A.O.I. C. Curceanu (Petrascu) briefly draw the attention to 2 new publications (November 2001). The first deals with the pion-nucleon sigma-term: being larger than in past (79+/-7 MeV), the strangness content of proton results in about 40%, by the use of "old" (1987) Gasser relation. DEAR results, namely kaon-nucleon sigma terms can be the key of solving this puzzle and to get the strange-quark condensate. The second publication is dealing with a calculation of neutralino-nucleon cross section calculation, starting from the pion-nucleon sigma term, with consequent cosmological implications. Since one of the main contributions comes from the strange-quark condensate, DEAR can give an input by calculating the kaon-nucleon sigma terms. So, new and interesting use of the DEAR data are just awaiting for the experimental results. (*) see the new schedule reported in the mail to dearcollaboration of 25/02/02 Catalina Curceanu (Petrascu) and Carlo Guaraldo Delete | Reply | Reply to all | Forward | Bounce | Resume | Save as Back to 2002 Move | Copy this message to:INBOX2001 2002 Drafts Salvate Sent Items drafts sent-mail sent-mail-feb-2003 sent-mail-jan-2003 sent-mail-mar-2003