LEP DATA PRESERVATION
11 years of data taking
4 Experiments
Large Luminosity
~1200 Scientific Papers
ALEPH
Raw data 5 Terabytes
DST 800 Gigabytes
Mini
80 Gigabytes
MC Files 16 T + 9 T
Similar for other experiments
History of Lep data archiving (1)
Interest triggered by CERN directorate in
year 2000.
 Formal agreement between LEP
experiments and IT department in 2001

http://committees.web.cern.ch/Committees/RB/RC.html

Working group active until 2004 with
partial success
History of Lep data archiving (2)

Development by IT of a "museum computing
system", based and frozen on existing lxplus
technology/software, with access possibilities to
(at present CASTOR) mass storage where all
data are stored.
These activities were started by Andreas
Pfeiffer and Tony Cass.
http://pfeiffer.home.cern.ch/pfeiffer/LEP-Data-Archive/Scenarios.html
History of Lep data archiving (3)

the safeguarding of 'standard' analysis
framework software and of mini-data on a
number of PC’s

the development of a modern C++ analysis
framework (in some cases)

the establishment of rules for access to data by
non-members of the Collaboration.
History of Lep data archiving- Aleph Statement (1)
The data collected by the Aleph experiment in the years 1990-2000 have been archived to
allow their use for physics analyses after the closure of the Collaboration. The archiving
includes the last set of simulated events and the most updated version of the analysis
software.
Limitations.
The available information is not sufficient to repeat all analyses, particularly when
systematic effects play an important role as, for instance, for precision measurements in
the electroweak sector. Examples of physics analyses that cannot be repeated on archived
data are
The measurement of the Z lineshape
The measurement of the W mass
The measurement of the tau polarization
The measurement of lepton and quark forward-backward asymmetries
Most heavy flavour measurements, such as the measurement of Rb, of the CKM
matrix elements, of Bd and Bs oscillations
The searches for the Higgs boson
Many searches in the Susy sector
History of Lep data archiving- Aleph Statement (2)
Authorized Users.
The use of archived Aleph data is authorized to former members of the Aleph
Collaboration and their collaborators. The use of a subset of data for teaching and
pedagogical purposes, under the guidance of former members of the Collaboration, is
allowed.
Authorship.
The publication of results based on archived Aleph data is not allowed until 1 year after
the official termination of the Collaboration, foreseen for the end of 2004. The authors of
the analysis take full responsibility for the publication. Any figure, plot or table using
Aleph data should contain the label “ALEPH Archived Data”. A reference to the present
document “Statement on the use of Aleph data for long-term analyses” must be present in
the publication.
Special Case : ALEPH QCD archive

http://aleph.web.cern.ch/aleph/
THE PROBLEM of HEP data preservation

The HEP data model is a highly complex data model (from
the start difficult to export to OA a` la astronomy)

Raw data -> calibrated data -> skimmed data -> high-level
objects

Final results depend on all the grey-literature on
constants, human knowledge, algorithms which are
needed for each pass

Experiment lifetimes > computing environment lifetimes.
Many migrations within the lifetime or an experiment (in
this sense preservation is not an issue !)
Lesson learned from LEP

Apart from publication of numbers or tables, no real OA Either little
useful or little usable (with small exceptions): continuous need for
additional knowledge, difficult to encode and store.

Regardless of community openness in pre-printing, wide-spreading
of preliminary results at conferences and insider information, little
priority on OA bringing to partial failures of LEP data archiving for
the "general" public.

Need force-majeure (Discovery at LHC of something we should
have seen at LEP?) to access data again.

Final results (containing additional unpublished information) but also
high-level objects have been already combined (LEP Electroweak
vs LEP Higgs)
The "Parallel way" to archiving and publishing data

In addition to internal data models, elaborate a parallel format for
useful and usable high-level objects

Publish high-level objects behind each scientific paper (after a time
lapse?)


Publish all high-level objects after end of collaboration
Address issues of accountability, reproducibility of results, "careless
discovers", "careless measurements"
A possible R&D program

Use LEP as a case study for information retrieval to better assess the
different methods

Define some high-level object to make a OA-based analysis possible
for an "external" but "motivated" researcher of the field

Propose strategies to define "parallel" high-level objects to be
included in the LHC data model, that is not post-mortem but aim to
make it part of the data-model designing process. This is very timely.

Imagine solutions to expand digital-library records of experimental
results to include the OA data behind the results

Initiate a discussion on priority issues and time-delays in making these
"parallel" high-level objects available. This is very timely.
Credit: to Salvatore Mele for many of the ideas in these slides