1. DATA TAKING – TESTS OF ABSORPTION LENGTH MEASUREMENTS IN ANTARES MC (group meeting) HAROLD YEPES-RAMIREZ IFIC, 22/10/10 1

2. DATA TAKING: During October has been possible to perform two sessions of optical properties runs (2 of the 3 weeks we have until now): 04/10/2010: 2 L8F9 L4F2 L8F2 L2F2(f1) L8F15 L2F2(f2) L4F15 L2F2(f3) L2F15 L2F2(f4) L2F9 L2F2(f5) L4F9 L2F2(f6) MAIN REMARKS OF THAT DAY: Each of them were classified as Golden runs. Rates around 80 kHz. All of them are high intensity runs. Towards the study of the change of the transmission/absorption length as a function of distance, different positions of the OB were considered. All Beacons located at storey 9, have shown the expected stability in time since some weeks ago. The runs taken with Beacons located at storey 15, due to the high intensity regime have reached the photoelectron region at certain distance were just two points remaining for the exponential fit  Not able to the transmission/absorption depth study  Low intensity runs at such distance were proposed.

3. 3 L8F9 L4F2 L8F2 L2F2(f1) L8F15 (LI) L2F2(f2) L4F15 (LI) L2F2(f3) L2F15 (LI) L2F2(f4) L2F9 L2F2(f5) L4F9 L2F2(f6) Week between 11/10/2010 and 17/10/2010: Rates around 160 kHz. Impossible to perform optical properties runs. 20/10/2010: MAIN REMARKS OF THAT DAY: Each of them were classified as Golden runs. Rates around 60 kHz. 3 low intensity runs taken for transmission/absorption depth study. A “tunning” was needed for the run setups, refereed to: * Relationship Beacon threshold – LED intensity – PMT gain. * Values were used for the first test: Beacon threshold: 150. LED intensity: 1200. PMT gain: 3900. Reason to use that values (for the three cases)  Only the Golden runs at low intensity we have come from such configuration refereed to L8F2 OB. Not events were recorded, however the size of the file looks normal  Ongoing analysis to find a suitable explanation. A new test with other “tunning values” have to be tested.

4. 4 TRADITIONAL PLOTS: L Vs runnumber MAIN DETAILS: After almost one month of the request of the 40 K sensitivity files to Dmitry Zaborov for September and October data  Dmitry is now at the HAWC collaboration, and he has told me that he is very busy, he promised to me send to me the sensitivity files ASAP… The stability after the strange runs batch were recovered (after runnumber 51000 approximately)  I have to re-start with the study of that strange effect.

5. 5 TRADITIONAL PLOTS: L Vs runnumber (Zoom) MAIN DETAILS: A change of the transmission/absorption length with the depth is not enough clear, however, the measurements taken with F9 Beacon, look to be more stable than the ones performed with the F2 Beacon.

6. 6 TRADITIONAL PLOTS: L Vs Prob(   ) MAIN DETAILS: Similar distributions obtained and presented in the lasts meeting groups and the last collaboration meeting. The effect of the small error assignment for one particular point in the exponential fit, seems to be the origin of the non-flat distribution we are expecting.

7. 7 TRADITIONAL PLOTS: Systematics studies (L2F2 Beacon) MAIN DETAILS: In total 5 sets of runs taken with the same Beacon with different faces (LEDs) to conclude the study of the OB systematics effects and to apply the correction by the angular acceptance. The point close to 70 m, is far due to the particular case of low Prob(  2 ) due to the commented small error assignment for one particular point in the exponential fit. Thinking about to use also L4F2 Beacon since we already have a first set of runs.

8. 8 TESTS OF ABSORPTION LENGTH MEASUREMENTS IN ANTARES MC Procedure I have follow: (I) Reading all material available of KM3 simulation package (GEN, HIT, KM3): http://antares.in2p3.fr/internal/dokuwiki/doku.php?id=monte_carlo In particular: http://antares.in2p3.fr/internal/dokuwiki/doku.php?id=km3 (A brief introduction to KM3) ANTARES-SOFT-2002-006 (detailed explanation about the package) http://antares.in2p3.fr/internal/dokuwiki/doku.php?id=triggerefficiency (For electronics smearing + background ) http://antares.in2p3.fr/internal/dokuwiki/doku.php?id=mcsummer2010 (Towards first comparissions for the official MC production for 2010 summer conferences) DONE

9. 9 Procedure I have follow: (II) Technical details with Annarita: * Create photon tables: Referred to modification in inputs parameter from GEN, HIT. DONE * Testing computing resources in Lyon for the special tests.DONE * Tests performed with the angular acceptance parameterization of june 2009, not the one used for Annarita, then, a special care about this details have to be checked; same concerning to the absorption length value of 60 m  WE ARE TESTING ONGOING * Annarita has been absent during some days due to the interruption in the Bologna mail server, her work with the APC people and as advicer of some work of NIKHEF people. However exchanged e-mails between us and Juan, suggest as priority, an scheme to begin with the “formal” simulations: Values for the absorption length to test Contribution of the scattering => Values of eta to test, contribution from rayleigh scattering.

10. 10 Water model. Trigger efficiency parametersTO DO.... * We just have to define the above statements. The scripts, computing time and other computing details are under control. * A very important thing to take into account is the special remarks of David Bayley (KM3 user guide) as the impact of our new inputs in order to check the sense of the results in the photon tables (as he has remarked along the KM3 guide and commented also by Annarita) => David: “Implicit things in GEN-KM3 which could affect the expected results for a given inputs...” => A special things to share with Annarita.TO DO