DELPHI

Overview

DELPHI was one of four large detectors on the Large Electron-Positron collider (LEP). It took 7 years to design and build, and it started up in 1989. In December 2000, DELPHI stopped taking data and was dismantled to leave room for the construction of the Large Hadron Collider in the LEP tunnel.

DELPHI consisted of a central cylinder filled with subdetectors, with two end-caps. It was 10 meters in length and diameter, and weighed 3500 tons. The detector consisted of 20 subdetectors. A large superconducting magnet sat between an electromagnetic calorimeter (for tracking electrons) and a hadronic calorimeter (to detect hadrons). The magnet generated a field to deflect charged particles so their charge and momenta could be measured.

The collaboration running the detector consisted of about 550 physicists from 56 participating universities and institutes in 22 countries.

Computing Environment

DELPHI binaries are distributed via CVMFS via /cvmfs/delphi.cern.ch. Several Linux distributions are supported. The binaries can be used directly from CVMFS, for example from lxplus.cern.ch, or via a virtual machine. The environment can also be run directly from any desktop which is both /cvmfs/delphi.cern.ch and /eos/experiment/delphi (or /eos/opendata/delphi) mounted, sourcing the environment from /cvmfs/delphi.cern.ch/setup.sh or /cvmfs/delphi.cern.ch/setup.csh (and pointing the environment variable DELPHI_DATA_ROOT to /eos/opendata/delphi if needed).

A quickstart guide and examples are available in https://gitlab.cern.ch/delphi

Please check the experiment home page for additional information, https://delphi-www.cern.ch

Accelerator
Host Lab
Public Page
Public Home
Internal Page
Collaboration Home
Contact Information
Greybook

DELPHI Status

Bit Preservation

State of the art bit preservation with regular scrubbing and migration to new media.

Data

Two copies on tape at CERN, one copy on disk, and one copy at external institute (University of Cantabria, Santander) with tape archive.

Documentation

To be archived in CERN Document Server for long-term preservation. Some software documentation on CernVMFS alongside the code.

Software

Binaries and source code published into CernVMFS. Software primary source is at https://gitlab.cern.ch/delphi

Use Cases

Continued analyses by former collaboration members. Discussing open access publication for education and outreach.

Audience

Primarily former collaboration. Open access data targeted at physicists and students, to be approved by the collaboration.

Value

Analyses, publications and PhDs continue to be produced

Uniqueness

Unique – until and unless certain FCC options are implemented

Resources

Minimal resources for bit preservation and storage. WLCG infrastructure for software on CVMFS.

Status

Data and simulated events are available on EOS. A DELPHI collaborator using CernVM may reconstruct and analyse the data and generate Monte Carlo events.

Issues
  • 32bit and 64bit binaries for Linux versions up to CentOS9 are provided albeit lacking full validation
  • the C++ analysis framework (IDEA) is provided 'as is'. It is untested and currently unmaintained
Outlook

Expect to be able to analyse data until at least 2032.

Until 2032 should be possible with < 1FTE / year

Links
Quick start guide https://gitlab.cern.ch/delphi/quickstart
cloud-init script on gitlab https://gitlab.cern.ch/delphi/delphi-preservation
Docker images for validation (requires authentication) https://gitlab.cern.ch/delphi/docker
DELPHI data preservation, re-use, and open access policy (2024) https://delphi-www.web.cern.ch/delphi-www/delsec/finalrules/DELPHI_Data_preserv…