Cosmic-Ray Physics with Icecube

Proposal Title: “LUX and High Energy Muon Induced Backgrounds in DUSEL”

Project Summary

The main goal of this proposal is to work toward a dark matter search experiment, the Large Underground Xenon (LUX) experiment in the U.S. Deep Underground Science and Engineering Laboratory (DUSEL), and to carry out a systematic study of the muon and muon-induced backgrounds in Davis Cavern by making full use of the data from LUX, especially those events that trigger in the 300-ton water shield.The proposed research and service work includes: (A) LUX integration and deployment, LUX water shield calibration, simulation, monitoring, and operation; (B) analysis of the data from LUX experiment for a systematic study of underground muons and muon-induced background signals in Davis Cavern;(C) building up a full Monte Carlo scheme to simulate muon induced backgrounds in DUSEL starting from cosmic ray primary fluxes, and improving the simulation by applying the progress in high energy muon production anticipated in IceCube. During the course of the research, we will alsomake contributions to educational outreach programs on the campus of South Dakota School of Mines and Technology (SDSMT) and through the administration of the EO office at Sanford Lab.

Intellectual Merit

By working on the LUX water shield calibration and simulation, we expect to have a quantitative description of the water shield veto efficiency against high-energy muons passing through it. By developing a proper calibration algorithm and precise simulation tools, we will be able to use the water shield for the measurement of muons and muon-induced backgrounds in Davis Cavern and in the dark matter detector. Such study is crucial in the background rejection and systematics estimation in the search for WIMP signals in LUX experiment. The background study will produce a comprehensive muon background profile at 4850 ft in DUSEL and reveal their correlation with signatures in the large Xenon detector, which will provide a benchmark for better understanding and more detailed simulation of the backgrounds for all forth-coming experiments in DUSEL. The study of modulations in LUX data, both experimentally and by simulation, and comparing them with modulations observed in IceCube will help us better understand this phenomenon and its effect in dark matter search analysis. By developing a full Monte Carlo background simulation starting from cosmic ray flux, we expect toeventually build up a Monte Carlo background library for DUSEL that also includes the fluctuations in air shower development and seasonal effects due to the change in the Earth atmosphere. After being improved over time, such a librarymay eventually serve all other experiments in DUSEL. Based on new results and ideas that may come out of our research, with the full Monte Carlo background simulation to be built during this funding period,we will be able to re-evaluate more quantitatively the necessity of having an appropriate surface array for DUSEL.

Broader Impacts

SDSMT is a major science and engineering university in South Dakota. It is also the major university closest to DUSEL. Building up a physics team with a post doctoral research fellow, graduate and undergraduate students and carrying out research work with LUX will not only produce scientific results, but also train young students so that we can make more contributions to future DUSEL research projects.

By working with the Education Department at Sanford Laboratory, such as giving lectures for the Davis-Bahcall and Fermilab-BNL-Homestake summer scholars programs, accepting Davis-Bachall program summer students to participate in our work with LUX in the Astroparticle Physics Lab at SDSMT, we expect to draw upon the science and engineering to be pursued at DUSEL to inspire and prepare the next generation of scientists, engineers and educators. South Dakota is also the home to nine Native American tribes. By working with Sanford Lab Education Department in SD GEAR UP Honors Program to provide an integrated approach to activities and lectures based on DUSEL, we expect toreach out to Native American students at all grade levels, attract and better prepare them to pursue higher education in science after their senior year of high school.