Monte Carlo Event Direction Distribution Codes ============================================== The different types of direction distributions used in INGENR and MCG_GENERATOR are: ID Mnemonic Description -- -------- ----------- -n none Give this particle the same direction as particle n (particle n must have already been generated). See warning. 10 IDAISO Generate all events isotropically. 20 IDABM Generate events in a beam. 30 IDACC Generate events with the proper directions for CC e-. See warning 35 IDANC Generate events with the proper directions for NC n. See warning 40 IDAES Generate events with the proper directions for ES e-. See warning 50 IDACONE Generate events on a cone. 60 IDAUSR Generate positions using user specified distribution. 70 IDALAS Generate events according to a distribution modelled by spherical harmonics to 2nd order. Intended for the laserball. The spherical harmonic coefficients are given in CALIBRATION_INFO.DAT 80 IDAPTG Generate events using the angular distribution needed for the (p,t) gamma source i.e. A+B*SIN^2(theta). The polar axis used is the PTG source axis if it is enabled otherwise it is the vertical axis of the detector. 90 IDACAV Generate events randomly within a cone pointing at the centre of the detector (Useful for generating gammas from the cavity wall). Alternatively generate events randomly on the surface of the cone (Useful for generating muons at a particular impact parameter regardless of position). As of SNOMAN 5 events can be generated either inwards (default) or outwards. 100 IDAPL Generate events with directions taken from a MCPL bank (see MCPL bank). 110 IDAPLED Generate events in a filled cone using the polynomial angular distribution needed for the LEDs mounted on the PSUP steel structure. 120 IDACOSMU Cosmic ray spectrum. 130 IDALSB Generate events on a non-pointlike laserball source, randomly picking the direction as a cos theta distribution centered on the radial direction from the center of the laserball. 140 IDANCDUSR Generate events with given zenith and azimuthal angles theta and phi. Theta is measured with respect to the z axis, (i.e. NCD anode) and phi with respect to the radial vector pointing *towards* the NCD wire. 160 IDAFCONE Generate events uniformly within a cone (as opposed to IDACONE which generates events on the surface of a cone) 170 IDALSBA Generate events on a spherical laserball source with distribution weighted by laserball mask and grid coefficients as read from LASR bank Model A ascribes anisotropies to distribution of both positions and directions - must be used wth corresponding POS type 180 IDALSBB As above, but Model B ascribes anisotropies to distribution of positions only - must be used with corresponding POS type 190 IDALSBC As above, but Model C ascribes anisotropies to distribution of directions only - must be used with corresponding POS type Notes: IDACC, IDAES and IDANC depend both on time and energy. When selecting this type of distribution make sure that the:- 1) Particle's time = IDTRATE 2) Particle's energy = IDECC, IDEES, or IDENC as appropriate. For the different distributions there are different input parameters to be stored in the DIR_PARAM array. These are: DIR Type Param. # Description -------- -------- ----------- 10 none 20 1,2 Detector theta, phi of beam. 30 1,(2,3,4) 0= time dependent (defined by IDTCCES), 1= fixed date (2= julian date, Ref: 1975 Jan 1, noon), 2= fixed source direction (2=x, 3=y, 4=z). 3= fixed Celestrial Coord (2=RA, 3=DEC, 4=GMST) 10 10=neutrino type (if IDECC also selected, should be the same) 35 1,(2,3,4) 0= time dependent (defined by IDTCCES), 1= fixed date (2= julian date, Ref: 1975 Jan 1, noon), 2= fixed source direction (2=x, 3=y, 4=z). 3= fixed Celestrial Coord (2=RA, 3=DEC, 4=GMST) 10 10=neutrino type (if IDENC also selected, should be the same) 40 1,(2,3,4) 0= time dependent (defined by IDTCCES) 1= fixed date (2= julian date, Ref: 1975 Jan 1, noon), 2= fixed source direction (2=x, 3=y, 4=z). 3= fixed Celestrial Coord (2=RA, 3=DEC, 4=GMST) 10 10=neutrino type (if IDEES also selected, should be the same) 50 1,2,3 x1,y1,z1 of a point at start of vector. 4,5,6 x2,y2,z2 of a point at end of vector. 7 theta. Points 1 and 2 define a direction, the directions are then distributed on the surface of a cone which makes an angle theta with this direction. 60 ? User defined. 70 none 80 1 Parameter A 2 Parameter B 3 Proton energy in MeV 90 1 Cosine of the half-angle of the cone. 2 Set to 0. to generate events inside the cone. Set not equal to 0. to generate events on the surface of the cone. 3 Set to 0. to generate events towards the center Set to negative value to generate events outwards 100 none 110 1,2,3,4 Parameter for polynom (angular distribution filling the cone) 5 maximal theta for the filled cone 120 none 130 1,2,3 x,y,z of laserball centre. 140 1 theta: zenith angle 2 phi: azimuthal angle, measured with respect to radial vector pointing *towards* NCD anode. 160 1,2,3 x,y,z direction vector for the center of the cone from (0,0,0) to (x,y,z) (does not have to be a unit vector) If the x,y,z direction vector is set to 0.,0.,0. then the cone direction is randomised for each event and recorded in a pre-source track. If cloning particles e.g. a photon bomb, the cone direction is only randomised once and then all the cloned particles will be picked randomly from the same cone. 4 opening angle of the cone (half angle from center) in degrees See Note 1 170 none 180 none 190 none Warning: Specifying a code of -n indicates that the value will be copied from the outgoing track of interaction number n where n is the interaction entry number within the MCPI. This can be ambiguous if the interaction produces multiple outgoing tracks e.g. a beta gamma decay. In this case the value will be taken from the FIRST outgoing track, but there is generally nothing significant to track ordering so you are advised NOT to link back tracks to such interactions. Note 1
The DIR_PARAM parameters for a filled cone (160) are converted to:- 1..9 (Except word 8) Rotation matrix: Maps point within cone into detector space. 8 Sneaky trick: Word 8 of matrix is identically zero so it is recycled as the logical flag. = 1. Fixed direction = 0. Random direction (not yet recorded in a pre-source for this event) = -1. Random direction (direction has been recorded in a pre-source for this event) 10 Cosine of cone opening angle