A Study of Photomultiplier Tubes Response to Scintillators Using Cosmic Rays, Ruthenium 106, and a Neutron Source. CHRISTINA FENNIMORE (Binghamton University Binghamton, NY 13902) MICHAEL SIVERTZ (Brookhaven National Laboratory, Upton, NY, 11973)

The KOPIO experiment is looking for a rare reaction to explain why matter and anti-matter are not equally distributed throughout the universe. KOPIO uses the AGS proton accelerator to create an intense beam of kaons to study rare decays. One of the rare decays is when a kaon decays into a neutral pion, a neutrino, and an antineutrino. This decay will help us understand CP (charge parity) symmetry violation. CP violation was discovered in 1960, when two different CP eigenstates decayed into the same products. CP violation can help scientists to understand how the universe began, and they are working towards studying CP violation in the KOPIO experiment. Prototype designs for KOPIO Charge Particle Veto detector were tested. The response to neutrons is a concern because the neutron flux is a thousand times greater than the kaon flux, so the response to neutrons was measured with a prototype CPV and a neutron source. Scintillator responses to a thermal neutron source were tested to understand the response of the KOPIO detectors. Scintillator responses were measured using photomultiplier tubes. The photomultiplier tube was calibrated by studying the response from a single photoelectron to see how many photoelectrons were produced. The photomultiplier tube has high amplification and low noise. The responses from cosmic rays and the radioactive source, ruthenium-106, were tested. By moving a 4x5 inch trigger scintillator across a 24.5x8 inch test scintillator the uniformity of response could be determined. The center and the edge of the test scintillator were tested to check the uniformity of the test scintillator. The photomultiplier tubes were attached to pieces of scintillator and the response to cosmic rays, ruthenium 106, and a neutron source were tested. It was found that the photomultiplier tubes were exceptionally responsive towards the neutron response. When further tests are done, the trigger threshold will need to be set at a much higher level. Future studies will establish the most receptive level for the threshold so that the kaons can be observed and the neutrons cannot.

Augmentation of Graphical User Interfaces for the Main Injector Neutrino Oscillation Search. ANDREW MCUMBER (Binghamton University Binghamton, NY 13902) MARY BISHAI (Brookhaven National Laboratory, Upton, NY, 11973)

Graphical user interfaces (GUI) in Java allow physicists straightforward access in managing classifications of streaming data from the networks of complex experiments. For the Main Injector Neutrino Oscillation Search (MINOS), a long-term study of muon neutrino flavors and their anomalous interactions, large volumes of sensor output are likewise conveniently displayed. The Java Analysis Studio 3 (JAS3) package is also implemented, chiefly for its numerous plotting capabilities and real-time data acquisition. The Fermi National Accelerator Laboratory project induces collisions of 120 GeV protons on a target, and observes a subsequent yield of hadrons, requiring that multiple charge monitors are present. Specifically, live proton beam target alignment in the Neutrino Main Injector (NuMI) is portrayed and updated in the GUI. Other critical characteristics of the software include a time plot of proton beam target intensity, a monitor for resultant pion and kaon particles, and muon detectors placed after the hadron decay reactions. An augmentation of existing code is undertaken, as a precautionary measure for budgeting and system alerts. A new GUI catalogues errors that are found by the local beam system. Detailed error categories are plotted and compared. Two trials for error rate monitoring are conducted and yield correlations between proton beam position devices, as well rate inequalities for different time periods in the NuMI research schedule. Memory management is characterized via a Java memory profiler.

Characterizing the interactions between a Photon and a Magnetic Field Gradient. CHERYL ANN BROWN (Borough of Manhattan Community College New York, NY 10007) DR. CAROL Y. SCARLETT (Brookhaven National Laboratory, Upton, NY, 11973)

The objective of this experiment is to explore an interaction between photons and a magnetic field gradient. The specific goal of our research is to detect the Fourth Order Feynman Interaction, Polarization of Virtual pairs, and/or Space Time Curvature. The method and main goal of our experiment was to apply Fourier Analysis with the software program FORTRAN. As a result of this, we then applied FORTRAN codes with a Fourier Analysis code to break down vibrations that can effect the photo-receiver sensitivity. By breaking down these vibrations, we can then find the amplitudes which are the frequency contributions to the wave as well as that particular frequency. Depending on the interference pattern, other sounds and vibrations (vibrations on the floor will jump around to about 120 Hertz, the additional vibration may be 60 Hertz that may influence the laser). We will then compare data from the accelerant-meter to the photo receiver of its vibration data with the data of the vibrations that we collect from the Fourier Analysis. With the aspect of Lens Calculations we prepared a data analysis table where, with the measurement of different optical lenses, a telescope to maintain space time curvature effect and a photo receiver at the end of the magnetic beam, we had the ability to calculate the focal point and minimize waist of the beam. To get the calculations of the radius of the beam at the photo-receiver, we applied an optical lens matrices and Jones vectors into a Mathematica program. We then applied several measurements of optical length to the distances of the laser beam and lenses to get precise data, measurements and price estimations for the Lens Experiment. The measured data that we have from the lens matrices and Jones vectors were set up as an "x" and "y" variables to see the proximity and sensitivity of the dimensions. Our results indicated that these dimensions provided the least amount of sensitivity in the waist of the beam, meaning that any lens shift within the error of our instruments would not dramatically affect the waist of our beam. Error bounds equal + -1cm. To conclude, the ultimate goal of our experiment was to eliminate outside interference, that contributes to the background noise and to eliminate it when trying to apply the authentic data.

Comparison of Particle Species and Spectra Produced in 25.5GeV/c Proton-Platinum Collisions for the KOPIO Experiment in Different Simulation Packages. KA HO LO (State University of New York - Stony Brook Stony Brook, NY 11794) DAVID JAFFE (Brookhaven National Laboratory, Upton, NY, 11973)

The KOPIO experiment(E926) aims at searching for the rare decay K_L → pi0 nu nubar with a predicted branching fraction of 3 x 10^-11. To study this decay, KOPIO requires a large flux of K_L beam. In the experiment, K_L are produced by having a 25.5GeV/c proton beam impinge on a stationary platinum target. Many particles species are produced in the collision. We need to purify the K_L beam as much as possible. Knowledge of the yields and the kinematic properties of the particles produced would be necessary for designing efficient ways of purification. Using Monte Carlo simulations(MC), we study the composition of the neutral beam. We used GEANT3 and GEANT4 for the study, which are MC packages used extensively in high energy physics. We compared the momentum spectra, time spectra and particle composition in different simulations. By comparing the simulation results, some discrepancies among the simulation packages are identified.

Control of Activated Soil in Building 912, the Alternating Gradient Synchtron (AGS) Complex. NOREEN SAPANSKI (St. Jospeh's College Patchogue, NY 11772) KIN YIP (Brookhaven National Laboratory, Upton, NY, 11973)

When high energy proton particles interact with the targets made of steel, concrete, and copper, a variety of radioactive atoms are produced. Below the targets and primary beam dump, some of these radioactive particles penetrate the concrete and iron layers of floor shielding. To assess whether Building 912 at Brookhaven National Lab sufficiently protects the activated soils below the floor, a scaled drawing of the floor shieldings of the Alternating Gradient Synchrotron (AGS) complex was converted using three dimensional geometry into Monte Carlo N Particle Extended (MCNPX) program. Using the beam line drawings and Monte Carlo calculations, a simulation of the radioactivity in the soil has been conducted. The results of these calculations were then used to draw contour lines in Building 912 that show activity concentrations in the groundwater beneath the soil. The results indicate that the high concentration of radioactive material in the soil lies primarily below the target at 2E-5 particles per cm2. These calculations are important because they reveal what happens to the activated soil below the target and beam lines if water penetrates into the activated soil. The output from the MCNPX simulation also indicates the location and size of the radioactive concentration in the soil. These results will also help determine if any changes need to be made in the boundary of the activated soil area so the drinking water is not affected.

Detecting Extreme Energy Cosmic Rays with RADAR. ELLYNNE KUTSCHERA (University of Wisconsin, Stevens Point Stevens Point, WI 54481) HELIO TAKAI (Brookhaven National Laboratory, Upton, NY, 11973)

Currently, cosmic ray showers are detected mainly through the use of scintillator arrays or related ground-based methods. An alternative means of detection may be possible, in particular for Extreme Energy Cosmic Rays. As cosmic ray showers move through the atmosphere, ionization is created. Depending on the energy of the primary cosmic ray particle, the angle of incidence of the shower, and the atmospheric depth of the shower, the ionization may even be dense enough to reflect incident radio waves. The density of the ionization at a given time and location, the position and shape of the ionization, electron lifetime as a function of attachment and recombination rates, and the geometry of radio reflection off the ionization must be understood in order to accurately predict what type of radio receivers are most appropriate for detection as well as where receivers should be located. Several sources of data are combined to describe a physical model of the EECR and radio reflection: simulated showers of EECR, data gathered on ionization lifetime, and geometric analysis of the shower ionization and ground reflection, or footprint. Calculations suggest that reflected radio signals of several microseconds should be receivable, available over areas of tens to hundreds of square kilometers. This information suggests particular types of receiving radio equipment and many possibilities for the placement of receiving antennas.

Development of Web Software for Nuclear Decay Data in the MIRD Format. MANUEL EMERIC (University of Puerto Rico Rio Piedras, PR 00923) ALEJANDRO SONZOGNI (Brookhaven National Laboratory, Upton, NY, 11973)

The Medical Internal Radiation Dose (MIRD) is the dose given to patient's organs during radiation therapy to destroy cancer cells. The organ doses used for a patient are not measured in vivo. The commonly used methods for deriving the organ doses are measurements done in a phantom, an artificial object representing a patient, or computer calculations. We have developed an easy to use web-based MIRD software product for the radiation dose data, which makes the nuclear decay data accessible for a larger group of users. Tables of nuclear and atomic radiations from nuclear decay and decay scheme drawings were produced in the MIRD format from the Evaluated Nuclear Structure Data File (ENSDF). A user interface was written in Hypertext Markup Language (HTML) code scripted with Java as a JSP file (Java Server Pages). The front page requests the user for the desired nuclide. The HTML form code and the JSP script send the nuclide name to the Java code classes that look for the information into the ENSDF database using Structured Query Language (SQL) commands. An image is created on the fly by Java classes showing the decay scheme for each decay mode of the desired nuclide as a ".png" (Portable Network Graphic) image shown with the results. The data results given by the MIRD interface consist of decay modes and their probabilities as well as radiation properties (type, energy, intensity and dose). The image includes energy for each level of the parent and daughter nucleus, level parity, decay mode label and ground state to ground state energy (Q-value). This work is part of the National Nuclear Data Center web page at Brookhaven National Laboratory available for the general public at www.nndc.bnl.gov .

Fourier analysis of background vibrations concerned with high level precision in the detection of virtual pair interaction and anomalous space-time curvature. DANIEL CARRERO (State University of New York - Stony Brook Stony Brook, NY 11794) CAROL SCARLETT (Brookhaven National Laboratory, Upton, NY, 11973)

Anomalous space-time curvature, analogous to that of general relativity, presents itself outside what is described by the standard model of physics concerning itself not with the induced curved flight path of a photon insofar as general relativity curves space around a massive object. Such photon interactions are not conceived adequately through the standard model which seeks to explain photon interactions as far as a 4th order Feynman interaction. Concerning this, our experiment wishes to facilitate the requirements of general relativity using an electromagnetic basis to further study such photon interactions. Thusly, in accordance to this objective, we will be utilizing a Relativistic Heavy Ion Collider (RHIC) quadra-pole magnet which upon being ramped at a frequency less than 20 Hz will yield a field gradient of 71 T/m where in which an argon laser of 512nm will pass and interact. The virtual pair interaction will resolve for us on a quadri-cell photo receiver, a frequent deviation of the beam equal to that of the magnetic ramping. Of consequence to us, the contribution of background vibrations can also provide deviations in the beam which can eliminate justified results. Therefore, we have worked to develop and analyze the Fourier transformations of background vibrations using comparative analysis of a photo receiver and accelerometer data taken over a span 1minute. Each device was positioned in critical areas near the magnet and the laser for 1 minute each and then alternated. Then utilizing FORTRAN running computers we transformed the vibrations into their components yielding various frequencies and contributions (amplitudes). Comparing the two devices we discovered similar vibration pickup and frequency contributions. From both, a clear and dominant 120 Hz signal was recovered which is expected from operation frequencies of cooling refrigerators surrounding the magnet. Of consequence to the magnet, signals near 20 Hz and below were negligible which gives good indication that background contributions to magnetic ramping will not contribute to false deviations. From these transformations, we are given a quantitative understanding of our background which will enable us to avoid in phase magnetic ramping which can leave ambiguity in our results.

Magnetization, Charge Transport, and Stripe Phases in Nd_5/3Sr_1/3NiO_4+d Single Crystal. JUN ZHANG (Cornell University Ithaca, NY 14853) MARKUS HUCKER (Brookhaven National Laboratory, Upton, NY, 11973)

Stripe phases, in which doped charges are localized along domain walls between antiferromagnetic insulating regions, provide a framework for the electronic structure of doped antiferromagnets such as the superconducting layered copper-oxides. Layered nickel-oxides, such as Nd_2-xSr_xNiO_4+d, though non-superconducting, exhibit stripe phases in which charges are more localized, resulting in higher charge density modulation amplitudes than their cuprate analogs, thus are more amenable for experimental investigations. We study the magnetic and electric-transport properties of a Nd_5/3Sr_1/3NiO_4+d single crystal by means of magnetic susceptibility, isothermal magnetization, and electric resistivity measurements. We observe a transition of the magnetic susceptibility with applied field parallel to the c-axis at T ˜ 15 K, which is due to the long-range ordering of Nd³⁺ magnetic moments. A transition of the in-plane resistivity ( _ab) is observed at T ˜ 230 K, which indicates the charge stripe ordering that has also been observed in La_2-xSr_xNiO₄ at about the same temperature. The out-of-plane resistivity ( _c) exhibits a milder transition at T ˜ 200 K. After the stripe phase transition takes place, the electronic transport exhibits variable range hopping behavior. The resistivity anisotropy ( _c/ _ab) shows a sharp drop at the _ab transition temperature with decreasing temperature, which indicates the strong localization of charge carriers in the ab-plane as charge stripes become statically ordered and the system becomes less two-dimensional electronically. Our results are in support of the stripe phase picture of the electronic structure in layered metal-oxides.

Optimization of the Muon Stopping Target of the Muon to Electron Conversion (MECO) experiment. DAVID MORSE (University of Rochester Rochester, NY 14627) YANNIS SEMERTZIDIS (Brookhaven National Laboratory, Upton, NY, 11973)

Muon to electron conversion is a rare symmetry violating process which MECO proposes to investigate. Natural muon decay in flight is characterized by the expression μ^-→e^-+ν_e(bar)+ν_μ. It is only in the presence of matter that the process μ^-+N→e^-+N is seen. This is a rare neutrinoless lepton flavor violating process with a maximum bound branching ratio of 10^^-11. This process is characterized by the production of a 105 MeV electron. This energy is the rest mass of the muon and shows a direct conversion. To produce these electrons muons are collided onto a muon stopping target. As such it is important to optimize this target for maximal muon stoppage and to retain high energy resolution (minimize energy loss) for resulting electrons. The target geometry initially proposed was a series of thin disks suspended in the transverse plane. After further study, other geometries were proposed, including a series of 17 cones pointing upstream or downstream of the muons, or a single larger cone pointing downstream. The cones were hypothesized to have a natural advantage over the disks, as the pitch of the electrons, the azimuthal angle from the particle's helical path, ensures that the electrons see less matter when traveling through an angled surface. Electrons lose 2 MeV per centimeter, so this is a major concern. Modifying existing GEANT (a GEometry ANd Tracking package) code, the target geometries were tested for both muons and electrons using ROOT, an object oriented data analysis framework, to compare muon stopping power, electron energy distributions and electron efficiency (what percentage of produced electrons reach the calorimeter). With a 24% increase in energy resolution and a slight increase in muon stopping power this analysis concludes that the series of cones pointing in the upstream direction is the most effective geometry for both muon stopping power and for minimizing electron energy loss.

Prototype Data Acquisition System for the Mixed Apparatus Radio-wave Investigation of Atmospheric Cosmic-rays of High Ionization (MARIACHI) Experiment. EBONY EGGLESTON (Florida A&M University Tallahassee, FL 32307) HELIO TAKAI (Brookhaven National Laboratory, Upton, NY, 11973)

Cosmic rays are high energy charged particles, originating in outer space, that travel at nearly the speed of light and strike the Earth from all directions. These primary cosmic rays contain mainly high energy protons, photons (gamma rays), and atomic nuclei. The MARIACHI experiment seeks to detect cosmic rays of energy 10E18eV or greater via detection of FM and TV band radio wave reflection from cosmic ray initiated ionization events in the stratosphere. The muse for MARIACHI came from a conventional method that radio astronomers detected meteorites and micrometeorites that entered into the Earth's atmosphere. Through the use of the data acquisition and instrument control software LabView, radio reflection waveforms will be acquired and analyzed. LabView is a computer software program which allows graphical development of an instrumental control, signal acquisition, measurement analysis, and data presentation which will enable the design and implementation of a Virtual Instrument (VI) for the analysis of the radio waveforms. The FM radio wave is conveyed from an antenna and incorporated into the LabView program, obtaining the audio waveform. Frequency discrimination analysis is then performed on the acquired waveform in order to determine whether the detected signal originates from stratospheric cosmic ray induced ionization. This will allow for the detection of signals only due to cosmic ray events. Due to the fact that the project is not yet complete, there are no results indicated. However, in conclusion, the objective of the LabView software is to be able to obtain those signals which are reflected from cosmic ray ionization events through the use of a PC controlled radio receiver and soundcard.

Prototype Data Acquisition System for the Mixed Apparatus Radio-wave Investigation of Atmospheric Cosmic-rays of High Ionization (MARIACHI) Experiment. SHANDA JOHNSON (Florida A&M University Tallahassee, FL 32307) HELIO TAKAI (Brookhaven National Laboratory, Upton, NY, 11973)

Cosmic rays are high energy charged particles, originating in outer space, that travel at nearly the speed of light and strike the Earth from all directions. These primary cosmic rays contain mainly high energy protons, photons (gamma rays), and atomic nuclei. The MARIACHI experiment seeks to detect cosmic rays of energy 10E18 eV or greater via detection of FM and TV band radio wave reflection from cosmic ray initiated ionization events in the stratosphere. The muse for MARIACHI came from a conventional method that radio astronomers detected meteorites and micrometeorites that entered into the Earth's atmosphere. Through the use of the data acquisition and instrument control software LabView, radio reflection waveforms will be acquired and analyzed. LabView is a computer software program which allows graphical development of an instrumental control, signal acquisition, measurement analysis, and data presentation which will enable the design and implementation of a Virtual Instrument (VI) for the analysis of the radio waveforms. The FM radio wave is conveyed from an antenna and incorporated into the LabView program, obtaining the audio waveform. Frequency discrimination analysis is then performed on the acquired waveform in order to determine whether the detected signal originates from stratospheric cosmic ray induced ionization. This will allow for the detection of signals only due to cosmic ray events. Due to the fact that the project is not yet complete, there are no results indicated. However, in conclusion, the objective of the LabView software is to be able to obtain those signals which are reflected from cosmic ray ionization events through the use of a PC controlled radio receiver and soundcard.

Scintillator Response to Neutron Radiation. RYAN KAUFMAN (SUNY Farmingdale Farmingdale, NY 11735-1021) L. LITTENBERG (Brookhaven National Laboratory, Upton, NY, 11973)

The KOPIO experiment (simply a pronunciation of the equation upon which it is based) is part of a scientific effort to study CP violation in the decay of $K^0_L$ particles into a $\pi^0$ and two neutrinos ($K^0_L\to\pi^0\nu\bar\nu$). This particular decay mode of $K^0_L$ is believed to exhibit direct CP violation which will be measured and studied. It must be distinguished from other, much more copious decays by the absence of extra charged particles in its final and intermediate states. When these charged particles pass through a scintillating plastic the subsequent light is measured and analyzed. Additionally, neutrons are going to be produced on the order of about two thousand neutrons to one $K^0_L$. Scintillators only give a signal when penetrated by charged particles, and the neutron, as we know, has no charge. It can, however, give a signal via a recoil proton or by neutron capture in the hydrocarbon scintillator. We used an Am/Be neutron source emitting neutrons in the thermal and energetic range. We tested a new scintillator, BC-408, wrapped in Tyvec and light sealed with photographic tape, as well as a complete shashlyk array with nine modules. The shashlyk array had eight modules surrounding one center module, the test module each with its own Thorn EMI 9903b PMT on one end. The PMT's were read out with ADC's (analog to digital converters) in a CAMAC (computer automated monitoring and controlling) crate. This should allow us to see a signal from the neutrons passing through the module directly, and veto signals coming in at angles to the test module, most likely cosmic ray muons. The thermal neutrons give a very low count rate. There is, though, a very high count rate due to the energetic neutrons. If most of the signal is due to energetic neutrons, as this should indicate, there should be more of a signal in the thermal neutron spectrum due to energetic neutrons penetrating the shielding. Simulations are going to be run to determine the source of this discrepancy This experiment will be very useful to any experiment in a neutron rich environment in which scintillators will be used to make measurements.

Single Gas Electron Multiplier (GEM) Based Gas X-Ray Detector and Ionization Chamber. RODNEY SNOW (Southern University and A&M College Baton Rouge, LA 70813) DAVID PETER SIDDONS (Brookhaven National Laboratory, Upton, NY, 11973)

The signal from an ionization chamber can be improved through the use of an electron multiplication device such as a gas electron multiplier (GEM). This paper will show the results from a one-inch diameter, single GEM based ionization chamber that was designed, built, and tested at the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory. The chamber was run with an Argon Carbon Dioxide (ArCO2 90/10) gas mixture at atmospheric pressure and achieved a gain of 130 at a 100 kV/cm field across the GEM. The detector was also characterized using Extended X-ray Absorption Fine Structure (EXAFS) and x-ray absorption near edge structure (XANES).

Single Gas Electron Multiplier (GEM) Based Gas X-Ray Detector and Ionization Chamber. JEOFFRI DAVIS (Southern University and A&M College Baton Rouge, LA 70811) DR. PETER SIDDONS (Brookhaven National Laboratory, Upton, NY, 11973)

The signal from an ionization chamber can be improved through the use of an electron multiplication device such as a gas electron multiplier (GEM). This paper will show the results from a one-inch diameter, single GEM based ionization chamber that was designed, built, and tested at the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory. The chamber was run with an Argon Carbon Dioxide (ArCO2 90/10) gas mixture at atmospheric pressure and achieved a gain of 130 at a 100 kV/cm electric field across the GEM. In the future, the detector will be further used to characterize samples using Extended X-ray Absorption Fine Structure (EXAFS) and x-ray absorption near edge structure (XANES).

Study on the Characteristics of Avalanche Photodiodes. ZACHARY PARSONS (University of South Dakota Vermillion, SD 57069) MILIND DIWAN (Brookhaven National Laboratory, Upton, NY, 11973)

In the past, many particle physics experiments have used Photomultiplier Tubes (PMTs) for light detection. These PMTs, while effective, have some limitations. One alternative is the Avalanche Photodiode (APD). APDs excel in many of these areas that PMTs are found lacking. While APDs are becoming more widely used, they are limited in size, due to increasing noise with increasing size. New techniques are in development to create larger area, high gain APDs with more favorable properties. This study was done to test the basic properties of new large area APDs developed by Radiation Monitoring Devices Inc. (RMD). The properties tested including dark current, gain, capacitance, and series resistance. The RMD APDs were compared to an older APD developed by Hamamatsu. For capacitance and series resistance measurements a LCR meter was hooked to the APDs. For dark current and gain measurements, a picoammeter was connected to the APDs. The capacitance per area for the RMD APDs is less than 1pF/mm2 at high bias. The series resistance is rather large, but is greatly reduced when it is specially packaged for use in water. The devices have a high gain, but the surface and bulk current is large. Overall, the results were promising, but further improvements are needed before the APDs are ready for use in experiments.

Test and Comparison of GEM Foils from Different Manufacturers Under Various Operating Conditions. PATRICK LYNCH (Bucknell University Lewisburg, PA 17837) CRAIG WOODY (Brookhaven National Laboratory, Upton, NY, 11973)

Gas Electron Multiplier (GEM) foils can serve as detectors for high-energy nuclear particles in a variety of physics applications. Because GEM foils are set to play a major role in upgrades to both the Pioneering High Energy Nuclear Interaction eXperiment (PHENIX) and Solenoidal Tracker At RHIC (STAR) experiments at the Relativistic Heavy Ion Collider (RHIC) located at Brookhaven National Laboratory, it is necessary to test the operation of these foils in regards to their gain and stability as a function of their operating conditions (e.g. pressure, water content in the gas), and as the foils' manufacturing processes are varied. Using a three GEM stack with an Iron-55 source in a 70/30 Argon/CO2 environment, the electrons produced can be collected and read off as an electronic pulse on an oscilloscope. Knowing the expected primary charge, a GEM foil's gain can be determined through a ratio of final charge to primary charge. When comparing the effect of pressure on the GEM foils' performance, a higher pressure was shown to lead to smaller gain. In addition, increased water concentrations in the detector environment not only resulted in a significant gain increase, but also improved the foils' overall stability. In the comparison of Tech Etch manufactured GEM foils and those manufactured at the CERN laboratory, the Tech Etch foils showed a significantly higher maximum gain, as well as much greater instability. The CERN foils had little to no charge up time (within minutes) at low water levels while the Tech Etch foils required several hours to reach their maximum gain potential. This work is imperative for finding the optimal operating environment for GEM foils so that they can be used effectively and accurately in their applications not only at Brookhaven Laboratory, but also in other research laboratories throughout the world.

Testing of Radiation Detectors for the Department of Homeland Security. PAUL ROVINSKY (Suffolk County Community College Selden, NY 11784) BIAYS BOWERMAN (Brookhaven National Laboratory, Upton, NY, 11973)

The Department of Homeland Security (DHS) is investigating the purchase of millions of dollars worth of radiation detectors. In order to assure that they perform the way the manufacturers claim, the DHS has assigned various government labs to test the manufacturer's claims. This study was primarily concerned with the hand-held radiation detectors, which work through gamma spectroscopy and may have neutron identification. Various sources at various distances are used to test their detection and identification capabilities. The testing method involves placing a source on a table and moving the detector farther and farther away at 0.3m intervals, to the 3m mark. The results vary, depending on the detector. Several detectors did not pick up any radiation above the background level beyond the 1.5m mark, but were still able to identify the source. Others were incapable of identifying the source but noticed the increased radiation. No detectors were able to identify all the sources. More testing will need to be done to draw any valuable conclusions, however, several of the detectors work magnificently under controlled conditions and are ready straight out of the box. The results of these tests will be sent to the DHS for use in determining which detectors will fulfill their needs best.

The Interactions of Virtual Pairs in the Electro-Magnetic Field. LISA SUTER (St. Joseph's College Patchogue, NY 11772) CAROL SCARLETT (Brookhaven National Laboratory, Upton, NY, 11973)

The purpose of this experiment is to study the behavior of virtual pairs while traveling through an electro-magnetic field. The effects that we will be looking for include photon-photon scattering, polarization of the virtual particles, and curvature with the presence of a gradient. Our setup will consist of a vacuum-sealed Relativistic Heavy Ion Collider (RHIC) quadra-pole magnet, which will produce a magnetic field gradient of 71 tesla/meter. We will be sending an argon laser through its cavity, producing 1019 photons/second. We want our equipment to be sensitive enough to detect photon-photon scattering. In order to detect a slight deviation in the lasers path, the waist of the beam has to be minimized. At the start of our setup, we will have a telescope designed to focus and minimize waist of the beam. At the opposite end of our magnet, a photon-receiver will be positioned to measure a deviation as small as 10 x 10-9 radians. In order to calculate the waist of the beam at the photo-receiver, we combined lens matrices and Jones vectors into a Mathematica program. A variety of optical lengths and distances between the laser and lenses were used in order to find the optimal measurements. We then set some of the measurements as variables, which allowed us to plot and measure the sensitivity of the dimensions. Our results indicated that the distances between the lenses had a greater influence on the radius of the beam then the optical lengths. Because of this, we focused more on the sensitivity of the setup by finding the rate of change between the distances and the waist. The focal lengths we used were -100 and 200. The distances that provided us with the best results were 67.1cm between the laser and the defocusing lens (D1) and 15.2cm between the two lenses (D2). With these measurements, we were able to produce a beam with a radius of 2 x 10-6 m at the photo-receiver. The rate at which the radius increased with any adjustment in D1 was also minimal with these dimensions. With this setup, we will be more accurate in finding any deviation in the path of the argon laser while traveling through the magnet. The trends that we were able to find though these calculations will also help us when preparing further studies with virtual pairs in the magnetic field.