T. Baker, K. Debry, B. Shen, R. Swertfeger
D. Whittington (Fairfield High School)
M.Sokoloff (University of Cincinnati)

The purpose of our research was to identify signal and background ranges of particle masses in high energy decays from the Large Hadron Collider beauty (LHCb), and to compare these masses to those recorded by the Particle Data Group (PDG) in order to confirm particle identification. We studied Ω_b^- to J/Ψ Ω^- , Ω_b^- to Ξ^- D⁰, and  Ξ_b⁰ to J/Ψ Ξ⁰(1530) decay channels by plotting particle properties such as momentum, probability of particle, lifetime, energy, mass, and invariant mass using 1D and 2D histograms. We used a linux terminal and ROOT program to write code in C++ that enabled us to graph and manipulate the large amount of data we were given. We applied many cuts on variables such as decay time and mass, fit the peaks with a gaussian fit, and compared the peaks to the mass values given by PDG. Our Ω_b^- mass was slightly different from that of LHCb’s recent studies, and should be further explored. We searched for but did not find the Ξ_b⁰ to J/Ψ Ξ⁰(1530) decay  through invariant mass plots. Additional research should be done to search for evidence of the  Ξ_b⁰ to J/Ψ Ξ⁰(1530) decay, and to verify the mass of Ω_b^- .

T. Baker, K. Debry, B. Shen,  R. Swertfeger
D. Whittington (Fairfield High School)
M. Sokoloff (University of Cincinnati)

The purpose of our research was to identify the signal and background regions in particle decay patterns and compare the measurements that to those listed in the Particle Data Group (PDG)  in order to verify the particles’ identification. We analyzed Ξ^-_{b ,} Ξ_b⁰ _, and Ω_b^-   decay channels by graphing the measurements such as invariant mass in one and two dimensional histograms while attempting to increase the clarity of the signal region by making “cuts” on the data through other measurements of the particle such as the lifetime, energy, and momentum of the particle decay. After making various cuts on the particle masses, we attempt to “fit” the peaks to a gaussian function to determine the most common masses. Comparing the masses to those on PDG, we are able to verify whether the unknown peaks are legitimate or inconclusive. By plotting Ξ^-_b mass, the histogram illustrated that the mass identified in the data (~5797 MeV) differed from that of the PDG mass (5791.1 ±2.2 MeV), alluding to a possible bias in the detector. In the Ξ_b⁰  decay channel we were able to confirm that  Ξ_b⁰  does indeed decay into Ξ^- π⁺J/Ψ by constructing invariant mass plot and isolating a strong signal at 5788 MeV, which is the mass of the parent particle Ξ_b⁰ . Furthermore, there appears to be a strong signal peak at ~3450 MeV in the Ξ_b⁰ decay; in the quest to determine this unknown signal, we compared the peak to a similar decay, that of Ξ^-_b . Alas, the the peak found at 3450 MeV was not a part of the Ξ^-_b. Further research may be done to to determine unknown peak at 3450 MeV along with the mass of Ω_b^-  particle. Additional data and effective cuts must be applied to find a more consistent mass. 

                          Cosmic Ray Detector Experiments      LBL 2014

Student                                 High School

Teacher                        High School

Purpose –The purpose of this experiment was for students to have hands on experience collecting & interpreting data from muon detectors. All students have had no previous experience using detectors. These detectors were supplied by Howard Matis of LBL.

Methods – After learning how to operate the detector, each of the 10 teams composed of 4 students, 1 teacher & a detector, choose one of the following investigations to determine the rate of flux of muon counts :

1. Tilting the detector between 0 and 90 degrees from the horizontal.
2. Shielding the detector with books, brass, water.
3. Changes in elevation of the detector over a distance of 5 floors.
4. Changing the east west orientation of the detector to determine if the collection were muons or antimuons due to right hand rule of electromagnetism.
5. Showing the angle of scattering by separating the paddles on a gamma source.  This was done by using a particle detector that was made at LBNL through QuarkNet over the last 8 years.

Results  - After collecting data groups returned to the large group to report.

                   Each group gave a presentation of their experimental design & results.

                   The findings are as follows:

1. The data showed the greater the tilt, the lower the flux & at 90 there were almost no counts.
2. There was no difference in flux with most of the materials we were able to use.
3. Groups did find a difference between the basement of the building & the fifth floor.  With the lower locations showing smaller rate of flux.  With group discussion it was determined this was due more to the buildings shielding effect than the small altitude difference.  However we can’t rule out the elevation difference entirely since one group collected data outside underneath a balcony minimizing the shielding .
4. There were 88 more antimuons than muons out of a total count of 1000. A student in the group clearly explained the set up, execution, & physics rules that explained this.
5. The group discovered that if the paddles were not in line at 180 degrees, the count falls off. There was much discussion regarding this experiment regarding the nature of the production of gamma rays.

Meaning & future investigations - Cosmic rays have played a large role in the development of Particle Physics.  The muon as well as antimatter were first detected by cosmic ray investigations.

This activity gave the students a first-hand experience in understanding & working with particles. Working with detectors also helped the students understand the collection of cosmic rays on much larger scales such as in ICECUBE.

Further investigations could include different shielding materials.