Changeset 1626 for trunk/MagicSoft/Simulation/Detector/ReflectorII/doc
- Timestamp:
- 11/15/02 21:52:19 (22 years ago)
- Location:
- trunk/MagicSoft/Simulation/Detector/ReflectorII/doc
- Files:
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- 1 deleted
- 2 edited
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trunk/MagicSoft/Simulation/Detector/ReflectorII/doc/Tdas0211.tex
r1618 r1626 59 59 information contained in this document is also present in MAGIC-TDAS 60 60 02-05 dealing with the previous version of the program, but it has also 61 been included here for clarity. An important bugregarding the62 ray-tracing routine ha sbeen corrected in this new version.61 been included here for clarity. Two important bugs regarding the 62 ray-tracing routine have been corrected in this new version. 63 63 \end{abstract} 64 64 … … 89 89 routine was checked in detail and some inconsistencies were 90 90 found. As a result of this, an important bug was detected which 91 produced a systematic blurring of all the images. This bug, fixed in 92 this version, is discussed in detail in section \ref{notes}. 91 produced a systematic blurring of all the images. Later another bug 92 was found in the calculation of the photon arrival time on the 93 camera.These bugs, fixed in this version, are discussed in detail in 94 section \ref{notes}. 93 95 94 96 %------------------------------------------------------------ … … 126 128 \section{Notes on version 0.6 \label{notes}} 127 129 128 \subsection { Thebug fixed in the ray tracing}130 \subsection {First bug fixed in the ray tracing} 129 131 130 132 The previous versions of the reflector were extensively checked and a … … 262 264 2$\pi$). When the direction cosines of a particle's trajectory are 263 265 given, they refer also to its momentum vector (a downgoing 264 vector). The same is true for the Cherenkov photons. 266 vector)\footnote{In Corsika the third component of the momentum is 267 measured along the negative z-axis and this is probably the origin of 268 the confusion which resulted in the bug}. The same is true for the 269 Cherenkov photons. 265 270 % 266 271 \begin{figure}[h] … … 307 312 course a paralel beam of light was focused at the right distance (1697 308 313 cm) since in that case u = v = 0, and both the upgoing and downgoing 309 versors have the same direction. 314 versors have the same direction. 310 315 \par 311 316 The example in figure \ref{parabola} shows the case in which the … … 408 413 dramatic effect than the defocusing which the bug was producing. 409 414 % 415 \subsection {Second bug: photon timing} 416 After a first release of Reflector 0.6 had been made public, another 417 important bug was found. We tried to check whether the simulated 418 reflecting dish was really ``isochronous''. A paralel beam of photons, 419 all sharing the same arrival time on the ground, were processed by the 420 simulation program and their arrival times on the camera plane were 421 histogrammed. The result can be seen in fig. \ref{timing} (dashed 422 histograms). This time the bug was quite evident: since Corsika gives 423 us the arrival time of photons on ground, the path from the point 424 where the photon hits the dish to the ground has to be subtracted (or 425 added, because since the center of the dish in the MC is at $z = 0$, 426 the mirror reflecting the photon may have $z < 0$ when the dish is 427 inclined). The sign in this subtraction (in {\it ph2cph.c}) was 428 wrong. This bug was present in both versions 0.5 and 0.4, and might 429 be related to the other one (a change of orientation of the z axis 430 at some point may have produced it). Since in the simulation made for 431 the design report the timing played little or no role (the camera 432 simulation did not consider the arrival times of photons) it is not 433 possible to know whether the bug was already in the code by then. 434 \par 435 This bug means that all the studies made up to now regarding photon 436 arrival times on the camera are completely useless (for instance, the 437 optimization of the time parameters in the L1 trigger has to be redone 438 from scratch!). 439 % 440 \begin{figure}[h] 441 \begin{center} 442 \epsfig{file=eps/timing.eps,width=\textwidth} 443 \caption{Test of reflector isochrony. The arrival time 444 distributions of photons in the camera are shown for (buggy) Reflector 445 0.5 and for Reflector 0.6. The sketch in the center shows the test for 446 the case in which the light beam is paralel to the telescope axis 447 (left plot). On the right, the same test has been made with light 448 arriving 1 degree off axis. 449 \label{timing}} 450 \end{center} 451 \vspace*{-1cm} 452 \end{figure} 453 410 454 \subsection {Performance of the new version} 411 455 In figure \ref{coma} we show the images of a point-like source at 10 … … 1026 1070 MagicProgs/Simulation/Detector/Reflector_0.6/doc/eps/spot_inf_f1697.eps.gz 1027 1071 MagicProgs/Simulation/Detector/Reflector_0.6/doc/eps/telecoor.eps.gz 1072 MagicProgs/Simulation/Detector/Reflector_0.6/doc/eps/timing.eps.gz 1028 1073 1029 1074 MagicProgs/Simulation/Detector/Reflector_0.6/tester/Makefile
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