1. ABSORPTION LENGTH MEASUREMENT/ IMPACT OF WATER PROPERTIES ON RECONSTRUCTION : STATUS HAROLD YEPES-RAMIREZ IFIC, March 09 th 2011 1

2. 2 ABSORPTION LENGTH MEASUREMENT

3. 3 INFLUENCE OF  R ON WAVELENGTH:  R  Average increased photon path length due to scattering. Two main concerns: 1.Is there a relationship with Kopelevich parameterization for scattering length?  R should be proportional to the scattering. METHOD (1): For 8 wavelengths available, extract the largest ones (referred to time of data taking) and the closer ones (referred to data of data taking) : 53793, 53795, 53798, 53799, 53801, 53803, 39660, 44552. Only for high intensity runs. Compute  R for the storeys used in the fit (which are in the photoelectron level) for each wavelength. Plot  R Vs for those storeys. Take a look on the results if all runs are considered (time effect on the time distribution tails) but all of them located at the same height (homogeneous photoelectron level criteria, F2). Each point on the graph correspond to the  R mean of the distribution and its RMS, wavelength and its width (case of all runs):

4. 4 Clarifications: hdt2  Histogram at 403 nm. There are mixed L12F2 and L6F2f2. SAME LED REFERENCE. hdt5  Histogram at 470 nm. There are mixed L1F2, L2F2, L4F2, L8F2. SAME LED REFERENCE.  R at OF  First floor of the fit; 1F  Second floor; ….

5. 5 OF – LARGEST RUNS OF – ALL RUNS 1F – LARGEST RUNS 1F – ALL RUNS

6. 6 2F – LARGEST RUNS 2F – ALL RUNS 3F – LARGEST RUNS 3F – ALL RUNS

7. 7 4F – LARGEST RUNS 4F – ALL RUNS 5F – LARGEST RUNS 5F – ALL RUNS ?

8. 8 COMMENTS (1): No Kopelevich trend is seen. The goal will be to see the behaviour for the scattering length itself. 5th degree Polynomial fit could represents the curve… No idea about direction to follow.

9. 9 METHOD (2): To confirm that  R should be proportional to the scattering  Different run intensity  Transmission length intensity dependence. F2 Photoelectron level [m] 70 m (F7) 100 m (F9) 125 m (F11) LED intensity Low (I 1 ) Medium (I 2 ) High (I 3 ) I 1 < I 2 < I 3 Scattering Low ( 1 ) Medium ( 2 ) High ( 3 ) 1 < 2 < 3

10. 10 Clarifications: Left plot  71 entries for high intensity at OF and beacon on the same height at 470 nm. Right plot  87 entries for high intensity, all beacons, 470 nm. Comments (2): Intensity ↑ ↑, Scattering ↑ ↑, L ↓ ↓, RMS ↑ ↑. Intensity ↓, Scattering ↓, L ↑, RMS ↓. Intensity ↓ ↓, Scattering ↓ ↓, L ↑ ↑, RMS ↓ ↓.  R technique at HI gives ~ 3 m to L: L = 55.4, L  R ~ 58 m (  = 1.06). How much can we get for MI and LI?: If  = 1.06 for LI, L  R ~ 64 m?

11. 11 The maximum decrease of the scattering effects can be reached at low intensity   R min ~ 11.32 m.  R min is less than the distance between storeys (R s-s ~15 m). If  R min < R s-s, can we sure that scattered photons are traveling such distance on average and then most of them reach the OM, being a very low amount of them the lost ones?  Could it be an enough correction due the scattering effects?  Is it the real absorption length? If the above statements are correct, the last step could be the final agreement between data and MC CALIBOB for low intensity runs at 470 nm (and the other wavelengths?). The data/MC difference could come mainly due this fact. If low intensity runs are the solution, attenuation length can be computed constraining the time integration gate from 1500 ns to a hundred of nanoseconds (or less than that)…L Vs Time integration gate (macros are ready) then scattering length can be computed as 1/att = 1/abs + 1/sca, then can be computed the effective scattering length.

12. 12 IMPACT OF WATER PROPERTIES ON RECONSTRUCTION

13. 13 1.COMMENTS ON THE SPECIAL MC PRODUCTION (GEN, HIT, KM3, GEASIM): SEED: GEN random number seed. INRAD, OUTRAD: inner and outer radius of the volume delimited by a pair of shells. SCALE_DIRECT, SCALE_SCAT: scale factor for direct and scattered photons associated with each shell. Track_ : id x y z vx vy vz E t Information about MC input tracks, hits and output of the reconstruction, references to track length. Proddate, prodtime: processing date (yymmdd) and time (hhmm) respectively. TopicDifferences GEN, HIT LEVEL: Me  SEED = 1000, Annarita  SEED = 0. Absorption-Scattering length input file (*.dat). No differences. Geometry files for shell photons propagation (*radii.out). 1 st and 2 nd columns are equal ( INRAD and OUTRAD ); 3 rd and 4 th columns very similar but not equal ( SCALE_DIRECT and SCALE_SCAT ). km3-*.desc.No differences. km3*.evt Me  SEED = 1000, track_in (1) = 11.69, track_in (1’) = 54.62. Annarita  SEED = 0, track_in (1) = 11.19, track_in (1’) = 45.38. KM3 LEVEL:No differences (same *.evt files). GEASIM LEVEL: simul: KM3 gea*.evt Differences on proddate and prodtime for obvious reasons. Me  track_in (1) = 54.62, track_in (1’) = 9.31. Annarita  t rack_in (1) = 45.38, track_in (1’) = 9.5.

14. 14 2.COMMENTS ON THE SPECIAL MC PRODUCTION (MCEW): --- A Margiotta --- H Yepes General (MCEW): Detailed table in next slide. Comparisson between similar productions: same angular acceptance, absorption length 63 m (me) and <63 m (Annarita) (last official neutrino production).

15. 15 DistributionsEntriesMeanRMS YepesMargiottaYepesMargiottaYepesMargiotta ident_ 9.87e69.48e66.88e35.67e311.22e39.07e3 pm_id_ 9.87e69.48e61.21e4 1.50e31.54e3 pure_dt_ 9.87e69.48e61.12e3 0.39e3 length_ 1.50e51.53e5-97-950.24e3 E_ 3.77e43.79e44.70e54.66e51.34e6 W3list_ 1.13e51.14e51.09e101.11e105.01e105.06e10 Weights 1.13e51.14e51.36e22 1.41e221.43e22 Remarks: The agreement for both productions is seen for the different kind of distributions, except for ident_ and pure_dt_ in which some entries are slightly shifted between them. Numerical comparison shows that non exact values are obtained but they are very close, referred to their entries, mean and RMS, except ident_.

16. 16 2.COMMENTS ON THE SPECIAL MC PRODUCTION (TE):

17. 17 DistributionsEntriesMeanRMS YepesMargiottaYepesMargiottaYepesMargiotta MaxA_ 1.21e41.11e413146.66.5 MaxT_ 1.21e41.11e42.10e82.08e81.17e8 MinT_ 1.21e41.11e42.10e82.08e81.17e8 TotA_ 1.21e41.11e43953451079.3886.7 Remarks: More entries for H Yepes distributions. General agreement, except for total amplitude (TotA_) distribution, however it is clearly seen the entries differences. Numerical comparison shows that non exact values are obtained but they are very close, referred to their entries, mean and RMS, except TotA_.

18. 18 QUESTIONS TO BE ANSWERED: MOST PROBABLY, ABSORPTION LENGTH CAN BE DIFFERENT BETWEEN THE TWO FILES (ME ONES AND ANNARITA ONES) SINCE NO OFFICIAL PRODUCTION IS AVAILABLE FOR NEUTRINOS AT 63 m OF ABSORPTION LENGTH (Annarita data might to be using a low absorption length). Do we have effects from SEED to the scale factor in the photon propagation geometry on each shell, length of the tracks in the volume? Are just the first tracks the affected ones (km3*.evt, gea*.evt files)? VERY SMALL DIFFERENCES, THEY ARE NOT ENOUGH WORRYING. A more robust analysis can go ahead. WHAT EXACTLY MEANS THE LABELS OF THE MCEW AND TE TREES? No documentation is available? The need of codes already done in order to be more efficient on the work, overall for data/MC comparisons before reconstruction (after reconstruction codes already created), i.e: number of OMs, number of lines, charge amplitude distribution, etc.