Based on the Los Alamos National Laboratory Digital Archive, we present our research into the use of the archive by authors and researchers from the international physics community. Professor Stevan Harnad, University of Southampton Dr. Les Carr, University of Southampton Tim Brody, Ian Hickman Open Citation Project - e-print e-mbryology

Growth of the LANL Archive Since the start of the archive in 1991 its usage has been steadily growing Now, after 10 years, it has over 130,000 papers

LANL Authors Number of unique names identified in each year *Before 1995 author meta-data is missing in most sub-fields Number of Identified Authors per Year

Citation Identification Based on automatic extraction and identification from the document source (Adobe Acrobat -.pdf) We have defined terminology for two types of citation: –Red-Link, an author cites a LANL pre-print article using a LANL reference (e.g. hep-th/ ) –Orange-Link, an author cites a post-print, published article that is also deposited in the archive (e.g. Phys. Rev. D (1997)) Identifies (Red + Orange) 600,000 citations of 3,000,000 total citations from 130,000 papers

Identification Ratio Currently 25% of citations are being identified

Identification Ratio - hep-th Currently 40% of citations from hep-th (High Energy Physics - Theory) papers are directly citing pre-print articles in LANL

Citation Latencies The raw data show that the latency of the citation peak has been reducing over the period of the archive

Citation Latencies Normalised data are corrupted by an artefact in the citation ratios (used to adjust for time)

Updates to LANL Pre-prints The LANL archive allows authors to update articles that they have deposited

Update Delay There are too few values to provide an accurate frequency so a trend must estimated

Article Embryology Papers with a journal reference [J-R] cross papers without a J-R at an age of 13 months, suggesting a time difference of 13 months between pre-print and post-print

Article State by Sub-field Self-professed state of the article (hep is updated by SLAC/SPIRES)

State of Cited Articles Broken down by papers written by authors with given impact level Author impact determined by Red-Link citations

Author Deposit Rates 50% of deposits of new papers occur within 4 months of the authors previous paper

Author Impact Analysis There is a co-author list for each paper Author impact is defined as the number of citations an author receives divided by the number of papers that author has deposited (the mean number of citations for an author) By applying this to each author, a list of author names with their impact is constructed The authors are ranked by their impact The set of authors is then divided into three impact sets; lowest 25%, middle 50% and highest 25%.

Author Impact Quartiles High impact authors update more than medium or low High and medium impact authors deposit more papers than low

Authors Papers There is no or little occurrence of the single high impact paper for the low impact author

Citation Spread A small number of papers receive a very large number of citations