MCformat.html

Format of the Monte Carlo block

Header [Size/Type=2100]
NH=NbHeaderWords {inclusive, here 8}

Event Weight {renormalised to have a reachable upper bound=1}
Versions [Format/MonteCarlo] {currently Format=1; MonteCarlo=260}
Generation seeds {2 words}
GEANT seeds {2 words}
NbWordsPerMeas {currently=9}

NI=NbInteractions
Pointers... to start of interaction information {NI pointers}
Interaction information block [repeated NI times]:

NV=NbVertices {primary and secondaries}
Pointers... to start of vertex information {NV pointers}
Vertex information block [repeated NV times]}:

Reaction type {such as interaction, decay, elastic scattering...}
Time at vertex
Xvertex
Yvertex
Zvertex
NP=NbParticles {primary and secondaries in arbitrary order}
Pointers... to start of particle information {NP pointers}
Particles information block [repeated NP times] :

pointer to Parent vertex
pointer to Child vertex {0 if absent}
particle code [GEANT conventions]
Px
Py
Pz
E
NM=NbMeasurements
Measurements information block [repeated NM times] :

Identification [Detector/Plane]
X {intersection
Y of track
Z with detector}
Time
Signal
X {momentum
Y components
Z at this intersection}

Non integer variables are scaled with a suitable factor and then stored as integers.

The units are micrometers, picoseconds and electron-Volts

All words are 32-bit long; the Header [Size/Type=2100] and the measurement Identification [Detector/Plane] are packed into two 16-bit words.

The pointers are relative to the first word of this block. This means that if the address of this first word, "Header [Size/Type=2101]", is iAdd, a pointer of value Ptr refers to a word at address iAdd+Ptr-1.

The system of reference is the secondary beam (Cs) for vertex co-ordinates and momenta.

The last component, "Measurements", is meant to replace the currently absent simulation of the sub-detectors response. This information could be later suppressed (changing the type of the MC-block from 2100 to say 2101, or/and changing the version). It could be kept as well if one feels this worth the lengthening of the file.
The "Format" component of the word "Versions" has been introduced. With value=1, a word has been added in the Header, "NbWordsPerMeas", to control the number of words per measurement (now=9, the last 3 were absent in the previous version).