MainPage:Nuclear:Summer2016:12GeVExp

Elastic Analysis, at CUA

File:123.pdf

Abstract

Previously, scientists believed pions and kaons, particles that constitute matter, were points without structure. With new research that theory has been proven incorrect. Next year Catholic University of America at Jefferson Lab will conduct a kaon experiment. The goal being to detect kaons with the Gas Cherenkov Detector of the High Momentum Spectrometer (HMS). The HMS measures the particles scattered by the electron when it hits the target proton. With this particle detection they hope detect, predict, and study the kaon particle’s form factor. In Addition, the experiment can be set up to detect both kaons and pions. This preferred set up that detects both kaons and pions will allow the researchers to study the Pion’s form factor as well. In order for both particles to be studied, the experiment must be optimized and set up correctly. To optimize the experiment code was typed and data analysis was used to determine the proper set up. Once, a simulation was run using previous data collected from a similar experiment at the Jefferson Lab. Then the total number of events from the similar experiment and simulation were plotted onto a histogram. Code was written in root that normalized and cut both data sets allowing them to be compared. The normalized data confirmed that the number of events was equal to the number of electrons sent or the actual yield. By studying the graphs insight into which aspects of the experiment to be done next year were optimized could be instituted such as different materials, angels, or methods. By detecting both sub atomic particles the experiment had the best chance to discover each particles form factor.

Personal Contribution Statement

During my summer internship with CUA (Catholic University of America) I ran simulations from previous trials. I then graphed the simulations with the previous results on a histogram. I tested and created code through CERN’s root program that normalized and cut the histograms. This allowed for it to be compared. It also confirmed the actual yield where the input equals the output. The comparison also allowed me to suggest where improvements could have been made by looking at where certain data was different than predicted. I helped to optimize the set up to best detect both kaons and pions.

Validating the Simulation with Previous Elastic data from Hall C

A Monte Carlo simulation, which is used to predict the probability of certain outcomes of events, needed to be validated in order to be used for the Kaon experiment set to run next year. As the Kaon experiment is completely theoretical, the simulation needs to give an accurate number of kaons and pions. Without an accurate number we would not be able to predict whether or not we could have insights into the pion form factor.

First, four input forms were created to mimic previously done elastic scattering experiments at JLab. The simulation was set up to track the scattered electron in the HMS (High Momentum Spectrometer) similar to the experiment.

Table 1:

The various input values are shown above. By changing the election momentum and angle, we can better learn our spectrometer.

Preliminary Results: shown below is a graph containing the simulations result superposed with the experimental recorded data.

The Graph only contains weights, normfac, and the prescale. The normfac accounts for the proper cross section. The prescale is needed because the computers can only pick up so many particles at once. Instead, it will measure for example one particle for every eighty that pass through to avoid crashing. Therefore the experimental data must be multiplied by eighty in this case to get the actual amount of data points. No cuts have been applied to the simulation's data.