|
|
# Millepede-II
|
|
|
|
|
|
## Introduction
|
|
|
|
|
|
Millepede II is the successor of Millepede, a package for linear least squares fits with
|
|
|
a large number of parameters. Both have been developed as experiment independent programs
|
|
|
by Prof. V. Blobel (Univ. Hamburg) primary for the alignment and calibration of tracking detectors. Documentation and source code of Millepede and of the first version
|
|
|
of Millepede II are available on
|
|
|
[his web page](http://www.desy.de/~blobel/mptalks.html)
|
|
|
(or [mirror](http://www.desy.de/~sschmitt/blobel/mptalks.html)).
|
|
|
Meanwhile, the Statistics Tools group of the Analysis Centre of the Helmholtz
|
|
|
[Terascale](http://terascale.de) Alliance took over the maintenance
|
|
|
of Millepede II.
|
|
|
|
|
|
The first Analysis Centre release, version V02-00-01, contains V. Blobel's 2009
|
|
|
development and small changes/fixes coming from CMS experience by G. Flucke.
|
|
|
Further development, mainly by C. Kleinwort for usage in CMS, adds
|
|
|
|
|
|
- auto-detection of bordered band matrices in the local fit to speed up processing if e.g.
|
|
|
fed with tracks fitted using the broken lines technique (cf.
|
|
|
[NIM A566:14-17,2006 by V. Blobel](http://www-library.desy.de/cgi-bin/spiface/find/hep/www?j=NUIMA,A566,14)
|
|
|
and *GeneralBrokenLines*),
|
|
|
- the possibility to ignore or compress rare off-diagonal elements of the global matrix
|
|
|
(to reduce space requirements),
|
|
|
- shared-memory parallelisation of most parts of the code (track fits, MINRES, inversion)
|
|
|
using [OpenMP™](http://openmp.org/wp),
|
|
|
- the possibility to read gzipped C/C++ binaries,
|
|
|
- further fixes/improvements not only from CMS experience.
|
|
|
|
|
|
Using these features allows CMS silicon tracker alignment to determine 200 000 parameters
|
|
|
in one go fitting more than 20 million tracks, including 3.6 million cosmic ray tracks
|
|
|
and about 375 thousand muon pairs from Z decays reparametrised as one fit object with a
|
|
|
vertex constraint and adding a virtual Z mass measurement (cf.
|
|
|
[CMS-CR-2011-323](http://cdsweb.cern.ch/record/1406822)).
|
|
|
The computing requirements on an Intel™ Xeon™ L5520 with 2.27 GHz using eight threads are
|
|
|
44.5 h CPU (but only 10 h wall clock time) and less than 32 GB of RAM.
|
|
|
|
|
|
## [Availability](availability)
|
|
|
|
|
|
## [Compilation](compilation)
|
|
|
|
|
|
## [Version history](history)
|
|
|
|
|
|
## [Hardcoded limits](limits)
|
|
|
|
|
|
## [Collection of users](users)
|
|
|
|
|
|
## [References](references) |
|
|
\ No newline at end of file |