ATLAS dataset nomenclature

Reference: ATL-COM-GEN-2007-003 "ATLAS Dataset Nomenclature" (2024 edition).

Data Identifiers (DIDs)

Rucio identifies all data objects via Data Identifiers in the form scope:name. For centrally produced ATLAS data the scope equals the project field (e.g. mc20_13TeV, data18_13TeV).

Data hierarchy:

events ∈ files ∈ datasets ∈ dataset containers ∈ campaigns

Note

The "dataset" physicists refer to in everyday conversation is usually a dataset container in Rucio — a collection of datasets from a single production campaign. When searching with rucio_list_dids, use did_type=container (the default) to find these.

Scopes

Scope pattern	Used for
`mc16_13TeV`	Run-2 MC, 13 TeV, ATLAS detector geometry
`mc20_13TeV`	Run-2 MC, 13 TeV, updated geometry
`mc21_13p6TeV`	Run-3 MC, 13.6 TeV
`data15_13TeV` – `data24_13p6TeV`	Real collision data by year
`user.<cern_username>`	Personal user datasets
`group.<atlas_group>`	Group-owned datasets

Monte Carlo format

project.datasetNumber.physicsShort.prodStep.dataType.AMITags

Example:

mc20_13TeV:mc20_13TeV.700320.Sh_2211_Zee_maxHTpTV2_BFilter.deriv.DAOD_PHYS.e8351_s3681_r13144_r13146_p5855

Field	Value	Meaning
`project`	`mc20_13TeV`	MC campaign, Run-2, 13 TeV
`datasetNumber`	`700320`	DSID — identifies the physics sample
`physicsShort`	`Sh_2211_Zee_maxHTpTV2_BFilter`	Generator, tune, process
`prodStep`	`deriv`	Production step
`dataType`	`DAOD_PHYS`	Output format
`AMITags`	`e8351_s3681_r13144_r13146_p5855`	Processing history chain

Real data formats

Primary datasets (individual runs):

project.runNumber.streamName.prodStep.dataType.AMITags

data18_13TeV:data18_13TeV.00348885.physics_Main.deriv.DAOD_PHYS.r13286_p4910_p5855

Physics containers (preferred for analysis — groups all runs in a period):

project.periodName.streamName.PhysCont.dataType.contVersion

data15_13TeV:data15_13TeV.periodAllYear.physics_Main.PhysCont.DAOD_PHYSLITE.grp15_v01_p5631

Use periodAllYear to get the full dataset for a given year, or specific period letters (periodA, periodB, …) for subsets.

AMI tags

AMI tags record the processing history of a dataset as a chain of single-letter codes followed by a version number:

Tier-0 (online/express processing):

Letter	Step
`f`	Reconstruction (bulk)
`c`	Reconstruction (commissioning)
`x`	Reconstruction (express)
`m`	Merging

ProdSys (offline processing):

Letter	Step
`e`	Event generation (evgen)
`s`	Detector simulation (simul)
`d`	Digitisation
`r`	Reconstruction
`p`	Group production / derivation
`t`	Merging
`n`	Event picking

Common data types

Type	Description
`DAOD_PHYS`	Full derivation — most complete, largest
`DAOD_PHYSLITE`	Lightweight derivation — preferred for analysis
`DAOD_EXOT*`	Exotic physics group derivations
`DAOD_SUSY*`	SUSY group derivations
`AOD`	Analysis Object Data — pre-derivation
`ESD`	Event Summary Data — large, rarely used directly
`EVNT`	Generator-level events
`HITS`	Simulated detector hits
`RDO`	Raw detector output

Other dataset types

Beyond MC and collision data, you may encounter:

Type	Format
Calibration	`dataNNN_calib.xxxxxxxx.calibration_<Det>-<info>.daq.RAW`
User datasets	`user.<cern_username>.<project>.<fields>.<dataType>.<versionTag>`
Group datasets	`group.<atlas_group>.<project>.<fields>.<dataType>.<versionTag>`
Conditions	`project.internalCondNumber.datasetUsage.COND`

Field length limits

Field	Limit
`scope`	≤ 25 chars
`name` (dataset)	≤ 255 chars
`name` (container)	≤ 150 chars
`project`	≤ 15 chars
`datasetNumber`	6–8 digits
`physicsShort`	≤ 50 chars
`dataType`	≤ 15 chars
AMITag (one tag)	≤ 32 chars

Finding MC job options

MC samples are defined by their DSID. Job options live in:

https://gitlab.cern.ch/atlas-physics/pmg/mcjoboptions/-/tree/master/<DSIDxxx>/<DSID>

where <DSIDxxx> is the first three digits of the DSID followed by xxx (e.g. DSID 700320 → 700xxx/700320).