project - SpecTcl Command

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Syntax

project [-[no]snapshot] sourcespec newspec x|y [contourname]

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Synopsis

Creates projections of 2d and gamma 2d spectra..

• -[no]snapshot controls whether or not the resulting spectrum will be incremented as a result of further event analysis. If -snapshot, the spectrum will remain static. If -nosnapshot or if the switch is omitted, SpecTcl will continue to increment the spectrum. See the Detailed Description below for information about conditions and foldings that might be applied to the projection.
• sourcespec is the name of a 2-d or gamma 2-d spectrum whose projection will be taken.
• newspec is the name of the new spectrum generated by the project command. This spectrum must not exist.
• x|y The projection direction. x means that for each x, the projection is done by summing channels for that x along the y direction. Similarly, y meanns that for each y, the projection is done by summing channels for that y along the x direction.
• contourname If present, this is the name of a contour (if 2-d spectrum) or gamma contour (if 2-d gamma). The contour must include all parameters in the source spectrum. Only the region inside the contour is projected in the specified direction.

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Detailed Description

Projections create new 1-d or 1-d gamma spectra (called the target spectrum) from existing 2-d or 2-d gamma spectrum (called the source spectrum) by taking a projection (possibily limited by a region of interest specified by a contour or gamma contour) in either the X or Y direction. There are two specific cases to consider.

• Projections of ordinary 2-d spectra.
• Projection of gamma 2-d spectra.

Projections of ordinary 2-d spectra

The result of projecting an ordinary 2-d spectrum is an ordinary 1-d spectrum. If the -snapshot switch is supplied, this spectrum will be frozen.

The target spectrum may automatically have gates applied to it. Gates will only be applied to targets that are not snapshot spectra. The intent of these gates is to ensure that the target spectrum increments in such a way that it remains a faithful projection of the source spectrum.

Automatic gating is as follows:

• If the source spectrum is ungated, and the projection is not via a contour, the target spectrum is gated with a "TRUE" gate (is ungated).
• If the source spectrum is gated, and the projection is not via a contour, the target spectrum is gated with the same gate as the source spectrum.
• If the source spectrum is not gated, and the projection is via a contour, the projection contour gates the target spectrum.
• If the source spectrum is gated, and the projection is via a contour, a gate is created that is the AND of these two gates and applied to the target spectrum. This AND gate will be named: __PROJECTIONGATE__roi__AND__sourcegate__ where roi is the projection contour and sourcegate is the name of the gate on the source spectrum.

Suppose, for example, we have a spectrum named pid_gamma which is gated on a gamma slice named 511kev, and that the X axis of this spectrum is an energy, while the Y is e.g. a de. Suppose this spectrum has a contour drawn on it (not applied to it) named 6Li. The command:

   project pid_gamma 6Li511kev x 6Li

Projections of gamma 2-d spectra

The target spectrum of a projection of a 2d gamma spectrum is a 1d gamma spectrum. If the -snapshot switch is supplied, the target is frozen.

The target spectrum may have gates and folds automatically applied to it. These gates and folds, in general, will not result in a continued faithful projection as the target spectrum increments, as the increments of gamma spectra are correlated within the sets of parameters gates and folds.

If the source spectrrum has a fold applied to it, the same fold will be applied to the target spectrum. Gates are applied to the target spectrum in the same way they are applied to ordinary 2-d projection targets.

Last Modified: May 27, 2005 by: fox@nscl.msu.edu
© Copyright NSCL 2005, All rights reserved