[u/mrichter/AliRoot.git] / ITS / doc / doc_ITS.html

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<FONT FACE="Albany, sans-serif"><FONT SIZE=4>============================================================================</FONT></FONT></P>
<P STYLE="margin-top: 0.42cm; margin-bottom: 0.5cm; page-break-after: avoid">
<FONT FACE="Albany, sans-serif"><FONT SIZE=4>Description of ALICE ITS
Code (Rev. 0.3 &#8212;  May, 16<SUP>th</SUP> 2008 &#8212; M. Masera)</FONT></FONT></P>
<P STYLE="margin-top: 0.42cm; margin-bottom: 0.5cm; page-break-after: avoid">
<FONT FACE="Albany, sans-serif"><FONT SIZE=4>============================================================================</FONT></FONT></P>
<P STYLE="margin-bottom: 0cm"><STRONG><FONT SIZE=4 STYLE="font-size: 16pt">Contents</FONT></STRONG></P>
<P STYLE="margin-bottom: 0cm"><BR>
</P>
<P STYLE="margin-bottom: 0cm"><A NAME="punto 1"></A>The goal of this
document is to give a concise description of the ITS software. For
more general information the reader is referred to the ALICE <A HREF="http://aliceinfo.cern.ch/Offline/AliRoot/Manual.html">offline
documentation</A>.</P>
<P STYLE="margin-bottom: 0cm">The reader is assumed to have a basic
knowledge of AliRoot and of the Inner Tracking System Detector.</P>
<P STYLE="margin-bottom: 0cm">The documentation is organized in the
following sections:</P>
<OL>
	<LI><P STYLE="margin-bottom: 0cm"><B><A HREF="doc_spd.html">SPD</A>.
	</B>This section gives information on SPD simulation, local
	reconstruction, calibration and specific run types. Author: D. Elia.</P>
	<LI><P STYLE="margin-bottom: 0cm"><B><A HREF="doc_sdd.html">SDD</A>.</B>
	As above. Author: F. Prino.</P>
	<LI><P STYLE="margin-bottom: 0cm"><B><A HREF="doc_ssd.html">SSD</A>.</B> As above. Author: E. Fragiacomo.</P>
	<LI><P STYLE="margin-bottom: 0cm"><B><A HREF="doc_itsgeo.html">Geometry</A>.</B>
	In this section a short description of the implementation of the ITS
	geometry used for simulation and reconstruction is given.</P>
	<LI><P STYLE="margin-bottom: 0cm"><B>ITS tracking.</B> This section
	provides information on the trackers used to prolong track
	candidates from the TPC (AliITStrackerMI class) and to find and fit
	tracks with the ITS alone (AliITStrackerSA). Information on cosmic
	muon reconstruction is also provided. <FONT COLOR="#dc2300">To be
	written</FONT>. 
	</P>
	<LI><P STYLE="margin-bottom: 0cm"><B>Primary vertex measurement.</B>
	This section describes the vertexers (AliITSVertexerZ and
	AliITSVertexer3D) used to provide a first estimete on the postition
	of the primary vertex position based on the local reconstruction of
	the 2 pixel layers. Author: M. Masera. <FONT COLOR="#dc2300">To be
	written</FONT>.</P>
	<LI><P STYLE="margin-bottom: 0cm"><B>Charged particle multiplicity.
	</B><SPAN STYLE="font-weight: medium">(Author: T. Virgili)</SPAN><B>
	</B> The charged particle multiplicity is determined with the
	<B>AliITSMultReconstructor</B> class, which measures the number of
	clusters and tracklets.<BR>A <I>tracklet </I>consists of two ITS
	clusters, one in the first pixel layer and one in the second. The
	clusters are associates if  differences in <I>Phi </I>(azimuth) and
	<I>Zeta</I> (longitudinal coordinate) are inside a fiducial region,
	defined by appropriate cuts These cuts depend on the interacting
	system (p-p or Pb-Pb) and can be set via <B>SetPhiWindow </B>and
	<B>SetZetaWindow methods. </B>In case of multiple candidates, the
	one with minimal azimuthal difference is chosen. <BR>It is also
	possible to control if two clusters in layer 2 can be associated to
	the same cluster in layer 1 or not. This is defined by means of the
	<B>AssociationChoice</B> (TRUE means double associations exluded;
	default = TRUE) method.<BR>The method <B>GetNTracklets</B> returns
	the number of tracklets and the relative information: <B>theta</B>
	and <B>phi </B>of the tracklet (as measured by layer 1), <B>Delta
	phi</B> (phi difference between layer 1 and 2), the label of the
	particle(s) producing the clusters.<BR>The unassociated clusters can
	be retrieved by the method <B>GetNSingleClusters</B>.<BR><BR>
	</P>
</OL>
<P STYLE="margin-bottom: 0cm"><BR>
</P>
<P STYLE="margin-bottom: 0cm"><BR>
</P>
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	2	<HTML>
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	5	<TITLE></TITLE>
	6	<META NAME="GENERATOR" CONTENT="OpenOffice.org 1.1.5 (Linux)">
	7	<META NAME="CREATED" CONTENT="20080430;10144900">
d6882b38	8	<META NAME="CHANGED" CONTENT="20080516;19440900">
2627be86	9	<STYLE>
	10	<!--
	11	@page { size: 21.59cm 27.94cm; margin: 2.01cm }
	12	P { margin-bottom: 0.2cm }
	13	-->
	14	</STYLE>
	15	</HEAD>
	16	<BODY LANG="en-US" DIR="LTR">
	17	<P STYLE="margin-top: 0.42cm; margin-bottom: 0.5cm; page-break-after: avoid">
	18	<FONT FACE="Albany, sans-serif"><FONT SIZE=4>============================================================================</FONT></FONT></P>
	19	<P STYLE="margin-top: 0.42cm; margin-bottom: 0.5cm; page-break-after: avoid">
	20	<FONT FACE="Albany, sans-serif"><FONT SIZE=4>Description of ALICE ITS
d6882b38	21	Code (Rev. 0.3 — May, 16<SUP>th</SUP> 2008 — M. Masera)</FONT></FONT></P>
2627be86	22	<P STYLE="margin-top: 0.42cm; margin-bottom: 0.5cm; page-break-after: avoid">
	23	<FONT FACE="Albany, sans-serif"><FONT SIZE=4>============================================================================</FONT></FONT></P>
	24	<P STYLE="margin-bottom: 0cm"><STRONG><FONT SIZE=4 STYLE="font-size: 16pt">Contents</FONT></STRONG></P>
	25	<P STYLE="margin-bottom: 0cm"><BR>
	26	</P>
	27	<P STYLE="margin-bottom: 0cm"><A NAME="punto 1"></A>The goal of this
d6882b38	28	document is to give a concise description of the ITS software. For
2627be86	29	more general information the reader is referred to the ALICE <A HREF="http://aliceinfo.cern.ch/Offline/AliRoot/Manual.html">offline
	30	documentation</A>.</P>
	31	<P STYLE="margin-bottom: 0cm">The reader is assumed to have a basic
	32	knowledge of AliRoot and of the Inner Tracking System Detector.</P>
	33	<P STYLE="margin-bottom: 0cm">The documentation is organized in the
	34	following sections:</P>
	35	<OL>
d6882b38	36	<LI><P STYLE="margin-bottom: 0cm"><B><A HREF="doc_spd.html">SPD</A>.
	37	</B>This section gives information on SPD simulation, local
	38	reconstruction, calibration and specific run types. Author: D. Elia.</P>
2627be86	39	<LI><P STYLE="margin-bottom: 0cm"><B><A HREF="doc_sdd.html">SDD</A>.</B>
d6882b38	40	As above. Author: F. Prino.</P>
	41	<LI><P STYLE="margin-bottom: 0cm"><B><A HREF="doc_ssd.html">SSD</A>.</B> As above. Author: E. Fragiacomo.</P>
	42	<LI><P STYLE="margin-bottom: 0cm"><B><A HREF="doc_itsgeo.html">Geometry</A>.</B>
	43	In this section a short description of the implementation of the ITS
	44	geometry used for simulation and reconstruction is given.</P>
2627be86	45	<LI><P STYLE="margin-bottom: 0cm"><B>ITS tracking.</B> This section
	46	provides information on the trackers used to prolong track
	47	candidates from the TPC (AliITStrackerMI class) and to find and fit
	48	tracks with the ITS alone (AliITStrackerSA). Information on cosmic
	49	muon reconstruction is also provided. <FONT COLOR="#dc2300">To be
	50	written</FONT>.
	51	</P>
	52	<LI><P STYLE="margin-bottom: 0cm"><B>Primary vertex measurement.</B>
d6882b38	53	This section describes the vertexers (AliITSVertexerZ and
2627be86	54	AliITSVertexer3D) used to provide a first estimete on the postition
	55	of the primary vertex position based on the local reconstruction of
	56	the 2 pixel layers. Author: M. Masera. <FONT COLOR="#dc2300">To be
	57	written</FONT>.</P>
d6882b38	58	<LI><P STYLE="margin-bottom: 0cm"><B>Charged particle multiplicity.
	59	</B><SPAN STYLE="font-weight: medium">(Author: T. Virgili)</SPAN><B>
	60	</B> The charged particle multiplicity is determined with the
	61	<B>AliITSMultReconstructor</B> class, which measures the number of
	62	clusters and tracklets.<BR>A <I>tracklet </I>consists of two ITS
	63	clusters, one in the first pixel layer and one in the second. The
	64	clusters are associates if differences in <I>Phi </I>(azimuth) and
	65	<I>Zeta</I> (longitudinal coordinate) are inside a fiducial region,
	66	defined by appropriate cuts These cuts depend on the interacting
	67	system (p-p or Pb-Pb) and can be set via <B>SetPhiWindow </B>and
	68	<B>SetZetaWindow methods. </B>In case of multiple candidates, the
	69	one with minimal azimuthal difference is chosen. <BR>It is also
	70	possible to control if two clusters in layer 2 can be associated to
	71	the same cluster in layer 1 or not. This is defined by means of the
	72	<B>AssociationChoice</B> (TRUE means double associations exluded;
	73	default = TRUE) method.<BR>The method <B>GetNTracklets</B> returns
	74	the number of tracklets and the relative information: <B>theta</B>
	75	and <B>phi </B>of the tracklet (as measured by layer 1), <B>Delta
	76	phi</B> (phi difference between layer 1 and 2), the label of the
	77	particle(s) producing the clusters.<BR>The unassociated clusters can
	78	be retrieved by the method <B>GetNSingleClusters</B>.<BR><BR>
	79	</P>
2627be86	80	</OL>
	81	<P STYLE="margin-bottom: 0cm"><BR>
	82	</P>
	83	<P STYLE="margin-bottom: 0cm"><BR>
	84	</P>
	85	</BODY>
3be246ab	86	</HTML>