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Performance Studies of Serial and Parallel Gas Distribution Systems in Monitored Drift Tube Chambers for the ATLAS detector at LHC, CERN Click here for a .pdf copy of the actual paper My
Division II gave me a well-rounded education in both physics and astronomy.
To close out the Division II, I participated in an REU (Research
Experience for Undergraduates) program at the State University of New York at
Stony Brook funded by the NSF. After
having spent the summer working at Stony Brook and nearby Brookhaven National
Laboratory, I have found that I am very interested in high-energy particle
physics. Within this REU program I
got to work closely with scientists collaborating on experiments involving the
PHENIX (Pioneering High Energy Nuclear Interaction
eXperiment) detector at RHIC (Relativistic Heavy-Ion Collider). Since this work was primarily theoretical, getting involved in some experimental research became an important goal for me. Therefore, for my Division III, I would like to participate with the ATLAS-Frascati group at Laboratori Nazionali di Frascati (LNF). I will spend 10 weeks with the group in Frascati from late August through early November, 2003. This group is helping to build the ATLAS (A Toriodal LHC ApparatuS) detector, which will be operating at the Large Hadron Collider (LHC) at the CERN Laboratory in Switzerland. The experiments involving the LHC make up the largest collaborative effort ever attempted in the physical sciences, involving 2000 physicists from more than 150 universities from over 30 countries. The Frascati group has the responsibility of building Monitored Drift Tube (MDT) chambers which will be mounted in the Barrell Middle Large (BML) stations of the ATLAS muon spectrometer. In the 2003 test
beam setup, the BML station is split into two sections (BML1 & BML2) and
each section is split into two multi-layers, resulting in four distinct
multi-layers. Each multi-layer is
made of three rows of 56 drift tubes filled with gas.
When a muon passes through a drift tube it ionizes the molecules in the
gas and leaves a trail of electrons. The
electrons then drift onto a wire that runs through the middle of the tube and
produces a measurable current. It
is possible to reconstruct the path of the muon by tracking which tubes produce
a signal and when they produce a signal. Therefore,
an important quantity to understand is the drift time, defined as the time that
it takes an electron to drift to the wire, because it tells us the position of a
muon track with respect to a given wire. One
of the goals of this recent test beam is to examine the difference between a
parallel gas distribution system and a serial gas distribution system and what
effect each has on the drift time. A
parallel gas system is one in which every tube has its own fresh input of
gas. Conversely, the serial system
(designed at LNF), pumps the gas through three tubes in series before flushing
and refreshing the gas. The MDT’s
of multi-layer 2 in the BML1 station use a parallel system while the remaining
three multi-layers of BML1 use a serial distribution system.
Previous results
from serial systems suggested that the drift time of the MDTs varied depending
on whether the tube was a gas input tube, a middle tube, or a gas output tube.
This analysis was initiated in order to discover whether there is a
dependence and, if a dependence exists, to understand the cause.
It has been hypothesized that water could be leaking into the system
through the hoses that connect the input, middle, and output tubes. My
involvement with the group will begin with analyzing data taken from the 2003
test beam. I will work to create a
series of macros in ROOT, an object oriented data analysis framework developed
at CERN, that will analyze the test beam data.
Once we are sure that we are observing this tube dependant effect of the
drift time, we can begin to explore the hypothesis.
This will involve running simulations with GARFIELD, a program designed
for drift chamber simulations. Through
these simulations, we will investigate what effect humidity levels could have on
the drift times. In addition, we
will try to develop a humidity correction factor from the simulated data. Applying this correction to the test beam data, we will try
to determine whether this humidity correction can account for the difference in
drift times. The
ATLAS-Frascati group has given me an account that grants access to the vast
array of computers available at LNF. This
is the main tool that I will need complete my project.
With this account, I can pipe into the LNF computers from anywhere in the
world that has internet access. In
addition, members of the ATLAS-Frascati group have committed to helping me
through this task. In particular, I
will be working closely with Maura Barone, Mario Antonelli, and Bellisario
Esposito. Piotr Decowski of Smith
College, who also works for SLAC at Stanford doing high-energy particle physics
(and is familiar with ROOT), is another resource for me throughout this project.
This is a great
opportunity for me to have a complete project that has a definitive beginning
and ending. It also differs from my
previous experience in that it is very experimental.
I will have the opportunity to work directly with raw 2003 test beam data
and be able to build a framework through ROOT that organizes, cuts, analyzes,
tests, and even evaluates real scientific data. This project should
result in an analysis note. In
addition to the note, I plan to write a paper outlining what modern particle
physics is and how it is carried out. Assuming
a knowledge of basic introductory college physics, the paper will give general
explanations of things such as calorimeters, colliders, bremsstrahlung, cherenkov radiation, and particle cross-sections.
Additional processes and physics, including the specifics of what
is involved in my project, will be described as well. My first Advanced Educational Activity will be an upper-level course during the Spring 2004 semester at Mt. Holyoke College, Analytical Mechanics – Physics 315. My second Advanced Educational Activity will be a teaching assistant position with Fred Wirth, NS102 – Musical Acoustics.
J. Kamin |