ZGOUBI USERS' GUIDE - HEP

4.2 Definition of an Object 39\PqîRq"po ¥}S"qo \"ro ¥| r"ro \"so ¥þ*"Xo \"ro ¥}¥I"to \@\ "uo ¥|§#"uo\ "wo ¥þr"uo1@@î@@@@@1R\Pq1\PB B B "vo ¤§ @ V¥|§#"1B B B "uo1ww1O V¥þr" qqîq\P1VOBJET: Generation of an objectOBJET is dedicated to the determination of the initial coordinates, in several ways.The first datum is the reference rigidity (a negative value is allowed)€ 4¡ ! 1 ! At the object, the beam is defined by a set of particles q (maximumO where is the relative momentum.Depending on the value of the next datum KOBJ, these initial conditions may be generated in six different ways:) with the initial conditions ( , , , ¥ , § , O )KOBJ = 1: Defines a grid in the , , , ¥ , § , O space. One gives the number of points desired,¤¦S"+¤ r"‹¤(r"‹¤¦¥I"‹¤§#"‹¤`O(maximum R q in each coordinate: ¤¦B BQB ¤ O) and the sampling sizeq and such that ¤_V¤ lV BEBDB V¤`Ozgoubi then generates ¤¦_V¤ lV¤lV¤¦¥mV¤§nV¤ O ( î) initial conditions with the following coordinates¥}S"‹¥| v"¥þr"‹¥}¥I"‹¥|§#"‹¥aOV¥}S" B B B " o ¤¦ @ V¥}S"V¥| r" B B B " o ¤ r @ V¥| r"V¥þ*" B B B " o ¤Œ @ V¥þ*"V¥}¥I" B B B " o ¤¦¥v @ V¥}¥I""uo ¥aO "wo V¥aO " B B B "uo ¤ OÜ @ V¥aO "\In this option relative momenta will be classified automatically for the purpose of the use of IMAGES for momentumanalysis.The particles are tagged with an index IREP possibly indicating a symmetry with respect to (§ , the ) plane, as explainedin option KOBJ = 3. If two trajectories have mid-plane symmetry, only one will be ray-traced, while the other will bededuced using the mid-plane symmetries. This is done for the purpose of saving computing time. It may be incompatiblewith the use of some procedures (e.g. MCDESINT, which involves random processes).). For instance the reference rigidity O isV¥|§#"The last datum is the reference of the ( problem, resulting in the rigidity of a particle of initial ¤;V¥aO condition to be"/"e"k¥"$§"O.¡ ! 1 ! ¤;V¥aO V1KOBJ = 1.1: Same as KOBJ = 1 except for the symmetry. The initial ¥ and conditions are the following¡ ! 1 !"xo ¥}¥I"yo B B B "uo VŒ¥}¥I"\This object results in shorter outputs/CPU-time when studying problems with symmetry.V¥þ*"¤V¥}¥I"¤¦¥KOBJ = 2: Next data: IMAX , IDMAX . Initial coordinates are entered explicitly for each trajectory. IMAX is the totalnumber of particles (IMAX ). These may be classified in groups of equal number for each value of momentum, inorder to fulfill the requirements of image calculations by IMAGES. IDMAX is the number of groups of momenta. Theîfollowing initial conditions defining a particle are specified for each one of the IMAX particlesv"‹r"‹¥I"‹§#"zO " ) ´ )S"+OWV¡ ! 1 !where is the rigidity (negative value allowed) and ´ )is a (arbitrary) tagging character.The last record IEX (I=1, IMAX ) contains IMAX times either the string “1” (which indicates that the particle will betracked) or the string “-9” (indicates that the particle should not be tracked).)This option KOBJ = 2 may be be useful for the definition of objects including kinematic effects.