Interpreting the output

This page provides detailed guidance for parsing and analyzing output files produced by the marley command-line executable. It begins with a description of the standard PDG codes used to identify particle types in all MARLEY simulation results. This is followed by documentation for each available output file format.

PDG codes

The Particle Data Group (PDG) has defined a standard numbering scheme for representing particle species in Monte Carlo event generators. Each kind of particle is assigned a unique positive integer as an identifier. The corresponding antiparticle is assigned a negative integer with the same absolute value. A full description of the numbering scheme is available here.

Like nearly all modern event generators used in particle physics, MARLEY adopts the integer PDG codes for particle identification and uses them both internally and in output files. For convenience, a table of the PDG codes most relevant for MARLEY is given below.

PDG code	Particle
11	$e^-$
12	$\nu_e$
13	$\mu^-$
14	$\nu_\mu$
15	$\tau^-$
16	$\nu_\tau$
22	$\gamma$
2112	$n$
2212	$p$
1000010020	$d$
1000010030	$t$
1000020030	$h$
1000020040	$\alpha$

In general, a PDG code of the form 100ZZZAAA0 represents a nuclide with proton number Z and mass number A. For example, $^{40}\mathrm{Ar}$ is represented by the PDG code 1000180400.

The HepMC3 event graph

The data structures defined by the HepMC3 event record library are used to implement the canonical representation of physics events in MARLEY v2.0.0 and later. To facilitate interoperability with other software tools used in neutrino physics, MARLEY also implements version 1.0.0 of the NuHepMC standard, which defines a set of conventions for representing neutrino interaction events within the HepMC3 infrastructure in a generator-agnostic way.

A key concept for reading MARLEY output files is the HepMC3 event graph. Each event is represented as a directed graph in which particles are the edges and vertices are the nodes. A vertex groups one or more incoming particles with one or more outgoing particles and typically represents a physical interaction. Every particle in a HepMC3 event is assigned a unique positive integer ID, and every vertex is assigned a unique negative integer ID. A particle that has no production vertex (i.e., an initial-state particle) is indicated by a production vertex ID of zero. Note that these IDs are used to index individual particles in the event graph; they are distinct from the PDG codes mentioned above that are used to differentiate particle species.

In a typical MARLEY neutrino-nucleus scattering event, the HepMC3 graph contains two kinds of vertices. The primary vertex represents the hard 2-to-2 interaction that produces the final-state lepton and outgoing nucleus. One or more de-excitation vertices may also be present in which the outgoing nucleus emits γ-rays, nucleons, or light complex fragments. Vertices representing particle emissions from the unbound continuum and from discrete nuclear levels are assigned distinct status codes, and a separate vertex is added to the event record for each binary decay step in the de-excitation cascade until the nuclear ground state is reached.

Output file formats

The generate, reweight, and decay commands accepted by the marley executable produce output files containing physics events stored within HepMC3 data structures. The generic description of a HepMC3 event graph can be serialized in multiple ways, and MARLEY currently supports both an ASCII text representation and (when built with ROOT enabled) a binary ROOT-based representation as official, full-featured output formats. The convert command can translate between these equivalent formats and also provide one-way conversions to some of the deprecated event formats used in MARLEY v1.2.1 and earlier. The summarize command creates a simplified “flat” ROOT TTree that stores a subset of the full event information for more convenient analysis. It replaces the functionality provided by the marsum executable that existed in the MARLEY v1 release series. Descriptions of the various output formats produced by these commands are given below.

ASCII HepMC3

A file in the ASCII HepMC3 format begins with a two-line header:

HepMC::Version 3.02.07
HepMC::Asciiv3-START_EVENT_LISTING

followed by a single run-info block and then one event block per simulated event. The file ends with the line:

HepMC::Asciiv3-END_EVENT_LISTING

Run-info block

The run-info block appears once at the start of the file and records information about the MARLEY run as a whole. Each line begins with a single-character tag.

W — weight names

A backslash-pipe (\|) separated list of the weight names defined for this run. MARLEY always declares at least CV (central value). If weight calculators were configured and used during a generate or reweight job, then additional weight names may appear later on this line:

W CV

T — tool identification

The generator name (MARLEY), version, and git commit hash, separated by backslash-pipes.

A — run-level attributes

Each A line stores one named attribute as A <name> <value>. MARLEY writes the following run-level attributes:

MARLEY.JSONconfig

The complete job configuration used to generate the events, serialized as a JSON string. This makes the file self-describing: all settings (reaction files, neutrino source, random seed, output paths, etc.) are recorded.

MARLEY.RNGseed

The integer seed that was used to initialize the random number generator.

MARLEY.ReweightConfig.<n> (reweighted files only)

The reweighting configuration applied by marley reweight, serialized as JSON. One attribute (indexed by the integer <n>) is written per reweighting pass applied.

NuHepMC.Version.{Major,Minor,Patch}

The version of the NuHepMC standard implemented (currently 1, 0, 0).

NuHepMC.Conventions

A space-separated list of the NuHepMC convention labels that MARLEY follows. For v2.0.0 output this is always:

G.C.2 G.C.3 E.C.1 E.C.2 E.C.3

These labels have the following meaning:

• G.C.2: The flux-averaged total cross section $\langle \sigma \rangle$ is known before the run begins and is stored once in the run-info block (see NuHepMC.FluxAveragedTotalCrossSection below), rather than being updated in each event as the generator runs.

• G.C.3: Citation metadata for MARLEY’s physics models is embedded in the run-info block (see NuHepMC.Citations.* below).

• E.C.1: Process IDs follow the NuHepMC recommended identifier ranges (100–199 for low-energy nuclear scattering, etc.; see the process ID table in the marley summarize section below).

• E.C.2: Each event records the total interaction cross section for the projectile at its sampled energy (tot_xs).

• E.C.3: Each event records the partial cross section for the selected primary interaction process (proc_xs).

NuHepMC.FluxAveragedTotalCrossSection

The flux-averaged total cross section $\langle \sigma \rangle$ for the run, in picobarns per target atom. This is the quantity needed to convert a distribution of simulated events into a cross-section prediction.

NuHepMC.Citations.Generator.{DOI,InspireHEP,arXiv}

Space-separated lists of the DOIs, InspireHEP keys, and arXiv identifiers for the papers describing MARLEY’s physics models. These should be cited whenever MARLEY output is used in a publication.

NuHepMC.ProcessIDs and NuHepMC.ProcessInfo[<ID>].{Name,Description}

The complete list of process IDs that may appear in events from this run, together with a name and description for each. Reading these entries directly from the file is the definitive way to interpret the signal_process_id event attribute.

NuHepMC.VertexStatusIDs and NuHepMC.VertexStatusInfo[<ID>].{Name,Description}

The vertex status codes used in the file and their meanings. MARLEY uses three codes: 1 (Primary, the primary interaction vertex), 22 (HFDecay, a continuum de-excitation step), and 23 (GammaDecay, a de-excitation step from a bound nuclear energy level).

NuHepMC.ParticleStatusIDs and NuHepMC.ParticleStatusInfo[<ID>].{Name,Description}

The particle status codes used in the file and their meanings. MARLEY uses five codes: 1 (Final-state), 4 (Projectile), 20 (Target), 27 (UndecayedRemnant, a nuclear residue before de-excitation begins), and 28 (IntermediateRemnant, a nucleus undergoing a de-excitation cascade).

NuHepMC.Units.CrossSection.Unit and NuHepMC.Units.CrossSection.TargetScale

The units for all cross section values in the file. MARLEY always uses picobarns (pb) per target atom (PerAtom).

NuHepMC.AdditionalParticleNumbers (and NuHepMC.AdditionalParticleNumbers[<PDG>].{Name,Description})

Particle codes used in the file that are not in the standard PDG numbering scheme. MARLEY declares PDG code 0, the Absent dummy projectile used in marley decay output (where there is no real incoming beam particle).

Per-event blocks

The first event block begins immediately after the run-info block on a line starting with an E character. An event block ends at the next E line or the end-of-file marker. The lines within an event block have the following structure.

E — event header:

E <event_number> <vertex_count> <particle_count>

For example, E 1 5 12 opens event number 1, which contains 5 vertices and 12 particles.

U — units:

U MEV CM

MARLEY always uses MeV for energies and cm for positions.

W — event weights:

W 1.0000000000000000000000e+00

One space-delimited weight value for each name declared in the run-info W line. For unweighted output from marley generate, only the CV (for “central-value”) weight appears and is always exactly one. In cases where additional event weight have been computed, their numerical values appear in the same order as the weight names listed in the run information.

A — per-event and per-particle attributes

Each attribute line has the form A <scope> <name> <value>, where the scope identifies the object to which the attribute belongs:

• 0: an event-level attribute.

• Positive integer: an attribute attached to the particle with this ID.

• Negative integer: an attribute attached to the vertex with this ID.

Event-level attributes (scope 0):

lab_pos

The interaction position in the lab frame as three space-separated values (x, y, and z; all in cm). Zeros are always given unless MARLEY has been interfaced with a separate detetor simulation.

signal_process_id

An integer code identifying the primary interaction type for this event. The meaning of each signal_process_id value is defined in the run-info block.

tot_xs

The total interaction cross section summed over all active processes, evaluated at the projectile’s sampled energy for the current event (pb per atom).

proc_xs

The partial cross section for the specific process selected as the primary interaction. This is evaluated at the projectile’s sampled energy for the current event (pb per atom).

MARLEY.GeneratorState

A serialized snapshot of the random number generator state. This attribute is written only by the generate command, and it appears only on the last event in the file. It is saved upon normal job completion or early termination (unhandled exception or user interrupt via ctrl+C). Its purpose is to support the resume output mode, which allows an interrupted generate job to continue exactly where it left off. For information about how to configure the resume output mode, see the example generate job configuration file (examples/config/annotated.js).

Particle attributes (positive scope = particle ID):

Ex

Nuclear excitation energy (MeV). This attribute is stored for particles representing an atomic nucleus. A value of 0 indicates the ground state.

twoJ

Two times the nuclear spin quantum number J. Doubling the value of J allows half-integer spins to be represented as integers. This attribute is stored for particles representing an atomic nucleus.

parity

Intrinsic parity (±1). This attribute is stored for particles representing an atomic nucleus.

charge

Net electric charge of the particle (integer, in units of the elementary charge). Written on atomic/ionic particles: the target atom and the outgoing nucleus at each stage of the de-excitation cascade. This records the charge of the atom or ion as a whole rather than of the bare nucleus, which is already encoded in the PDG code. When the particle’s charge can be unambiguously determined by PDG code (as it can for elementary particles), this attribute is not stored.

P — particle lines

Each particle in the event is described by a P line:

P <id> <prod_vtx_id> <pdg> <px> <py> <pz> <E> <mass> <status>

id is the particle’s unique positive integer identifier within the event. prod_vtx_id is the ID of the vertex that produced this particle (negative integer), or 0 for initial-state particles that have no production vertex. pdg is the particle’s PDG code, px, py, pz, E, and mass are the 3-momentum components, total energy, and mass, all in MeV. status is one of the particle status codes defined in the run-info block.

V — vertex lines

Each vertex is described by a V line:

V <id> <status> [<parent_particle_ids>]

or, for vertices with a non-zero spacetime position:

V <id> <status> [<parent_particle_ids>] @ <x> <y> <z> <t>

id is the unique negative integer identifier for the vertex. status is one of the vertex status codes defined in the run-info block. The bracketed list gives the IDs of the particles entering this vertex (i.e., particles for which this is their end vertex). The optional @ x y z t suffix gives the spacetime position in cm and cm/c; it is present for de-excitation vertices that have a non-zero time delay and omitted otherwise.

Worked example

The following ASCII-format HepMC3 event represents a charged-current primary interaction $\nu_e + \, ^{40}\mathrm{Ar} \to e^{-} + \, ^{40}\mathrm{K}^*$ followed by a chain of four γ-ray emissions from nuclear de-excitations. Momenta and energies in the P lines are rounded to three decimal places for readability; an actual MARLEY output file would use enough digits to preserve full double-precision for all floating-point numbers.

E 1 5 12
U MEV CM
W 1.0000000000000000000000e+00
A 4 Ex 4.3837
A 6 Ex 2.28987
A 8 Ex 1.64364
A 10 Ex 0.0298299
A 12 Ex 0
A -5 GammaBranchingRatio 1
A -4 GammaBranchingRatio 0.803859
A -3 GammaBranchingRatio 0.562746
A -2 GammaBranchingRatio 0.757576
A -5 TotalWidth 1.07350060716826e-13
A -4 TotalWidth 1.35785047037652e-15
A -3 TotalWidth 5.4968404583917e-09
A 2 charge 0
A 4 charge 1
A 6 charge 1
A 8 charge 1
A 10 charge 1
A 12 charge 1
A 0 lab_pos 0.000000 0.000000 0.000000
A 4 parity 1
A 6 parity 1
A 8 parity 1
A 10 parity -1
A 12 parity -1
A 0 proc_xs 6.05325088059723e-05
A 0 signal_process_id 100
A 0 tot_xs 7.45272521695649e-05
A 4 twoJ 0
A 6 twoJ 2
A 8 twoJ 0
A 10 twoJ 6
A 12 twoJ 8
P 1 0 12 0.000 0.000 21.200 21.200 0.000 4
P 2 0 1000180400 0.000 0.000 0.000 37224.7 37224.7 20
V -1 1 [1,2]
P 3 -1 11 -7.848 -7.396 11.564 15.821 0.511 1
P 4 -1 1000190400 7.848 7.396 9.636 37230.1 37230.1 27
V -2 23 [4]
P 5 -2 22 0.134 1.298 -1.637 2.094 0.000 1
P 6 -2 1000190400 7.713 6.098 11.273 37228.0 37228.0 28
V -3 23 [6] @ 0.000 0.000 0.000 1.001e-03
P 7 -3 22 0.373 -0.320 0.419 0.646 0.000 1
P 8 -3 1000190400 7.340 6.419 10.854 37227.4 37227.4 28
V -4 23 [8] @ 0.000 0.000 0.000 4.150e+03
P 9 -4 22 -0.834 -0.559 1.264 1.614 0.000 1
P 10 -4 1000190400 8.174 6.978 9.590 37225.7 37225.7 28
V -5 23 [10] @ 0.000 0.000 0.000 4.294e+03
P 11 -5 22 0.019 -0.021 0.010 0.030 0.000 1
P 12 -5 1000190400 8.154 6.999 9.580 37225.7 37225.7 1

Walking through this event:

• Particles 1 and 2 are the initial-state particles: an electron neutrino (PDG 12, status 4 = Projectile) with kinetic energy ≈ 21.2 MeV travelling along the z-axis, and a stationary ⁴⁰Ar nucleus (PDG 1000180400, status 20 = Target) with rest mass ≈ 37224.7 MeV. Their production vertex ID is 0, indicating they are initial-state particles with no production vertex in the graph.

• Vertex −1 (status 1 = Primary) represents the primary interaction, with particles 1 and 2 as inputs. It produces two outgoing particles.

• Particle 3 is the final-state electron (PDG 11, status 1 = Final-state, mass ≈ 0.511 MeV). Particle 4 is the $^{40}\mathrm{K}^*$ nuclear residue (PDG 1000190400, status 27 = UndecayedRemnant) in an excited state with excitation energy $E_x = 4.3837 \; \mathrm{MeV}$, spin $J = 0$ (twoJ = 0), and positive parity. This discrete nuclear level is the isobaric analog of the $^{40}\mathrm{Ar}$ ground state.

• Vertices −2 through −5 (all status 23 = GammaDecay) are successive de-excitation steps simulated using tabulated γ-ray branching ratios. Each takes the intermediate nuclear remnant (status 28) as input and produces one γ-ray (PDG 22, status 1) and a new remnant at a lower excitation energy. Vertices −3, −4, and −5 carry an @ … t suffix showing the time of each de-excitation step in cm/c; the first step (vertex −2) has no time suffix, meaning it is treated as instantaneous (due to an unknown nuclear level half-life). The Ex attributes on particles 4, 6, 8, 10, and 12 trace the excitation energy at each stage of the cascade: 4.3837 → 2.28987 → 1.64364 → 0.0298299 → 0 MeV.

• Particle 12 (status 1 = Final-state) is the $^{40}\mathrm{K}$ nucleus in its ground state after the cascade is complete.

The signal_process_id of 100 identifies this as a charged-current interaction that populates a discrete nuclear energy level (vCC-discrete as defined in the run-info block). The proc_xs and tot_xs attributes give the cross sections at this event’s neutrino energy: the process cross section ≈ 6.05 × 10⁻⁵ pb and the total cross section ≈ 7.45 × 10⁻⁵ pb per target atom.

ROOT HepMC3

If MARLEY has been built with ROOT support (see the Getting started page for build instructions), full HepMC3 events can also be stored in ROOT’s compressed binary format. The ROOT HepMC3 format is an equally full-featured representation of the events, not merely a subset or summary.

MARLEY uses its own reader/writer classes (OutputFileRoot and EventFileReader) built around the HepMC3::GenEventData and HepMC3::GenRunInfoData plain-data structs from the official HepMC3 library. It does not use HepMC3’s WriterRoot or ReaderRoot classes.

A ROOT HepMC3 file produced by MARLEY contains:

• A TTree named MARLEY_event_tree with a single branch named event holding one HepMC3::GenEventData object per event.

• A HepMC3::GenRunInfoData object named MARLEY_run_info containing the run-level metadata (the same information as the run-info block in the ASCII HepMC3 format).

Opening a MARLEY ROOT HepMC3 file

After sourcing the setup_marley.sh environment script, one may open a MARLEY ROOT file directly in a ROOT session:

source setup_marley.sh
root -l some_events.root

The libMARLEY library and its ROOT dictionary are loaded automatically by ROOT’s autoload mechanism. One can then browse the raw event data, for example:

MARLEY_event_tree->Scan("particles.pid:particles.status", "", "", 20)

The GenEventData struct fields available for browsing include particles (a vector of GenParticleData structs with fields pid, momentum, status, etc.), vertices (a vector of GenVertexData structs), and event_number, among others.

For most analysis purposes, the recommended approach is to use one of MARLEY’s built-in tools rather than navigating the HepMC3 data structures directly:

• marley print — display events in a human-readable format.

• marley convert — translate between output formats.

• marley summarize — produce a flat ROOT ntuple (described below) for convenient histogram-level analysis.

Advanced users who need more complete access can write their own analysis code that links against the HepMC3 library (libHepMC3) directly, using HepMC3::GenEvent::read_data() to reconstruct full event objects from the stored GenEventData structs. This requires the HepMC3 headers and shared library to be available at build time and runtime.

Summary ROOT TTree

The summarize command reads one or more MARLEY HepMC3 event files (in either the ASCII or ROOT format) and writes a flat ROOT ntuple suitable for quick analysis. This is a convenience projection of the full HepMC3 event record: it removes many details of the event history while exposing the most commonly-needed information. The summary ROOT TTree cannot be converted back into the full HepMC3 event format.

Usage:

marley summarize -o summary.root events.hepmc3

Multiple input files may be given; they are concatenated in the order specified after checking for consistency of the configurations given in each run-info block. The output file contains a single TTree named mst (“MARLEY summary tree”) with one row per event. A std::vector< std::string > object called MARLEY_other_weight_names also appears in the file and stores the names of any weights beyond the central-value weight (CV) that appeared in the original HepMC3 events.

The example ROOT macros in examples/macros/ all consume the mst tree produced by marley summarize; see examples/macros/README.md for details. None of these example macros operate on raw ROOT HepMC3 files directly.

Branch listing

The primary interaction is a 2-to-2 collision (projectile + target → ejectile + residue), where the projectile (target) is the lighter (heavier) initial-state particle. Four-momenta are evaluated in the laboratory frame (where the target particle is at rest). The ejectile (residue) is the lighter (heavier) final-state particle. De-excitation products (γ-rays, neutrons, etc.) are the particles produced after the primary reaction.

Projectile

pdgv (int)

PDG code of the projectile.

Ev (double)

Projectile total energy (MeV).

KEv (double)

Projectile kinetic energy (MeV).

pxv, pyv, pzv (double)

Projectile 3-momentum components (MeV).

Target

pdgt (int)

PDG code of the target.

Mt (double)

Target mass (MeV).

Ejectile

pdgl (int)

PDG code of the ejectile.

El (double)

Ejectile total energy (MeV).

KEl (double)

Ejectile kinetic energy (MeV).

pxl, pyl, pzl (double)

Ejectile 3-momentum components (MeV).

Residue

pdgr (int)

PDG code of the residue.

Er (double)

Residue total energy (MeV).

KEr (double)

Residue kinetic energy (MeV).

pxr, pyr, pzr (double)

Residue 3-momentum components (MeV).

Residue state immediately following the primary interaction

Ex (double)

Excitation energy of the residue immediately after the hard interaction and before any de-excitations (MeV).

twoJ (int)

Two times the spin J of the residue.

parity (int)

Parity of the residue (±1).

De-excitation products

np (int)

Number of de-excitation products (γ-rays, neutrons, protons, etc.) produced during the nuclear de-excitation cascade.

pdgp (std::vector<int>)

PDG codes of the de-excitation products.

Ep, KEp (std::vector<double>)

Total energies and kinetic energies of the de-excitation products (MeV).

pxp, pyp, pzp (std::vector<double>)

3-momentum components of the de-excitation products (MeV).

tp (std::vector<double>)

Production time for each de-excitation product (seconds). The primary interaction occurs at time $t = 0$.

Cross section and process information

xsec (double)

Flux-averaged total cross section for the run (10⁻⁴² cm² per atom). This value is the same for every event in a given run; it is stored per-row for convenience.

proc (int)

Process ID indicating the kind of primary interaction that occurred in the current event. The recognized codes are given in the table below.

ID	Name	Description
100	vCC-discrete	Charged-current neutrino scattering on a nucleus that induces a transition to a discrete (bound) nuclear energy level
101	vCC-continuum	Charged-current neutrino scattering on a nucleus that induces a transition to the unbound continuum at excitation energies above the particle-emission threshold
110	anti-vCC-discrete	Same as vCC-discrete (100) but with an incident antineutrino
111	anti-vCC-continuum	Same as vCC-continuum (101) but with an incident antineutrino
150	NC-discrete	Neutral-current (anti-)neutrino scattering on a nucleus that populates a discrete (bound) energy level of the outgoing nucleus
151	NC-continuum	Neutral-current (anti-)neutrino scattering on a nucleus that populates the unbound continuum
700	v-e	Elastic scattering of (anti-)neutrinos on atomic electrons
800	standalone-decay	Standalone nuclear de-excitation (decay command; no primary interaction)

Event weights

cv_weight (double)

The central-value (CV) event weight. For normal event generation with MARLEY, the central-value weight is always unity.

other_weights (std::vector<double>)

Any additional weights assigned during a generate or reweight job. These appear in the same order as the strings in the MARLEY_other_weight_names vector mentioned above. The other_weights vector may be empty if MARLEY_other_weight_names is also empty.

Legacy MARLEY v1 format

MARLEY can produce event files in the native text format used in v1.2.1 and earlier via marley convert --output-format legacy. This is a one-way conversion provided for backward compatibility; the legacy format is deprecated and cannot be produced by the generate command.

HEPEVT

The legacy HEPEVT output format was officially supported in the MARLEY v1 release series and is still available as an option for the convert command. The description presented here covers only those aspects of the HEPEVT format needed to interpret the output of MARLEY. Further details are available on pages 327–330 of this document.

A HEPEVT-format output file consists of one or more text-based event records. Each of these records begins with the header

NEVHEP NHEP

where NEVHEP is the event number (untracked by MARLEY and thus always set to zero) and NHEP is the number of particles in the event. The header is followed by NHEP lines, each representing a single particle. These have the format

ISTHEP IDHEP JMOHEP1 JMOHEP2 JDAHEP1 JDAHEP2 PHEP1 PHEP2 PHEP3 PHEP4 PHEP5 VHEP1 VHEP2 VHEP3 VHEP4

where ISTHEP is an integer code identifying the particle status and IDHEP is the particle’s PDG code. In agreement with the HEPEVT standard, MARLEY uses status code 1 for the final-state particles and 3 for the initial-state particles. The JMOHEP1, JMOHEP2, JDAHEP1, and JDAHEP2 entries record the indices (between 1 and NHEP, inclusive) of particles in the event record that correspond to the first mother, second mother, first daughter, and last daughter of the current particle, respectively. These indices are set to zero in cases where they do not apply (e.g., a particle with no daughters will have JDAHEP1 = JDAHEP2 = 0). Entries PHEP1 through PHEP3 record the x-, y-, and z-components of the particle 3-momentum, while PHEP4 gives the total energy and PHEP5 gives the particle mass (all in GeV). Entries VHEP1 through VHEP3 store the x, y, and z positions of the particle production vertex (mm), and VHEP4 gives the production time (mm/c).

In addition to the initial- and final-state particles, MARLEY adds a dummy particle with ISTHEP = 11 to each HEPEVT event record. All data fields are zero for this particle except for (1) JMOHEP1, which contains the nuclear spin multiplied by two, (2) JMOHEP2, which reports the parity of the nucleus as an integer, (3) PHEP4, which gives the excitation energy of the nucleus (MeV), and (4) PHEP5, which records the flux-averaged total cross section in units of MeV:sup:-2 per atom. The excitation energy, spin, and parity values in the HEPEVT record refer to the nuclear state that is formed after the primary interaction but before any de-excitations have occurred.

0 7
3 12 0 0 0 0 0.00000000000000000e+00 0.00000000000000000e+00 1.00000000000000002e-02 1.00000000000000002e-02 0.00000000000000000e+00 0. 0. 0. 0.
3 1000180400 0 0 0 0 0.00000000000000000e+00 0.00000000000000000e+00 0.00000000000000000e+00 3.72247225431518061e+01 3.72247225431518061e+01 0. 0. 0. 0.
11 0 2 1 0 0 0.00000000000000000e+00 0.00000000000000000e+00 0.00000000000000000e+00 3.79748000000000019e+00 5.98368867447267264e-19 0. 0. 0. 0.
1 11 0 0 0 0 -4.63535385338761496e-03 1.35706546730579320e-03 -1.87687187323011366e-03 5.20690886815266749e-03 5.10998927645907710e-04 0. 0. 0. 0.
1 1000190400 0 0 0 0 4.98066184879143812e-03 -2.27058729207187593e-03 9.28456410767741942e-03 3.72257175068044077e+01 3.72257159465162459e+01 0. 0. 0. 0.
1 22 0 0 0 0 -1.11400145523226908e-03 9.50751758100756655e-04 4.66119350851738206e-04 1.53694352434620668e-03 0.00000000000000000e+00 0. 0. 0. 0.
1 22 0 0 0 0 7.68693459828445808e-04 -3.72299333346743093e-05 2.12618841470095347e-03 2.26118395490674000e-03 0.00000000000000000e+00 0. 0. 0. 0.
0 6
3 12 0 0 0 0 0.00000000000000000e+00 0.00000000000000000e+00 2.99304885549511283e-02 2.99304885549511283e-02 0.00000000000000000e+00 0. 0. 0. 0.
3 1000180400 0 0 0 0 0.00000000000000000e+00 0.00000000000000000e+00 0.00000000000000000e+00 3.72247225431518061e+01 3.72247225431518061e+01 0. 0. 0. 0.
11 0 2 1 0 0 0.00000000000000000e+00 0.00000000000000000e+00 0.00000000000000000e+00 1.03964200000000009e+01 5.98368867447267264e-19 0. 0. 0. 0.
1 11 0 0 0 0 -9.86795370224160216e-03 -1.55256312663347770e-02 -2.09630900945356009e-03 1.85223477954320724e-02 5.10998927645907710e-04 0. 0. 0. 0.
1 1000190390 0 0 0 0 -1.74322423197586264e-02 -4.21863040207651613e-02 5.85225771236273160e-02 3.62940260743929031e+01 3.62939501877290738e+01 0. 0. 0. 0.
1 2112 0 0 0 0 2.73001960220002303e-02 5.77119352870999400e-02 -2.64957795592226236e-02 9.42104609518426450e-01 9.39565378653339778e-01 0. 0. 0. 0.

The listing above shows an example MARLEY output file in HEPEVT format.