Pion correlations as a function of atomic mass in heavy ion collisions Page: 26 of 130
Pages: (120 p)View a full description of this report.
Extracted Text
The following text was automatically extracted from the image on this page using optical character recognition software:
CHAPTER 3. MOTIVATION AND THEORY
source would give an apparent source size that would decrease as a function of the pion
energy.
3.4 Experimental Correlation Function
In the experiment the correlation function is defined to be the ratio of the two particle
cross section to the product of two single particle cross sections with a normalization
factor
C L(PA P2) - D dd (3.15)
where D is a normalization constant, de/dpi dpi, the two-pion inclusive cross section,
and dco/dp3, the single-pion inclusive cross section. While it is in principle possible to
measure the various cross sections separately, that is not usually done. Usually, in nuclear
collision experiments, the single pion cross sections (the background) are estimated from
relative momentum spectrum of like-sign pions from different events (event mixing).
The reasons for using event mixing are outlined below:
Using mixing of unlike-sign pions has the difficulty that the spectrometer can only
detect one sign of particle at a time. Assuming that triggering difficulties and the proton
contamination could be dealt with, twice the beam time would be needed to do the
experiment. There is also the theoretical uncertainty due to the different production
rates of x+ and a- and the different distributions of the protons and the neutrons in the
nucleus.
Using theoretical methods to generate the background has the difficulty that nuclear
collisions are not understood well enough to predict what the two-particle momentum
spectra would be in the absence of the Bose-Einstein effects. There is also the objection
of using the model that is to be tested to generate the data that are supposed to be testing
the model.
Simply measuring the single pion momentum spectrum has the difficulty that the
number of pions produced in the nuclear collision depends on the impact parameter.
Therefore, the requirement of two pions in the spectrometer biases the two-pion trigger
towards more central collisions than the one-pion trigger[1]. The one-pion triggered dataI'6
Upcoming Pages
Here’s what’s next.
Search Inside
This report can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Report.
Chacon, A.D. Pion correlations as a function of atomic mass in heavy ion collisions, report, November 26, 1989; Berkeley, California. (https://digital.library.unt.edu/ark:/67531/metadc1055804/m1/26/: accessed July 18, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.