BEGIN:VCALENDAR
VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-8825
DTSTART:20240827T180000Z
DTEND:20240827T200000Z
DTSTAMP:20260413T171840Z
LAST-MODIFIED:20240716T031343Z
LOCATION:Sterling Hall\, Room B343
SUMMARY:Cosmology and HI Intensity Mapping\, Thesis Defense\, John Pod
 czerwinski\, Physics PhD Graduate Student
DESCRIPTION:This thesis is focused on the HI intensity mapping techniq
 ue. I begin by reviewing basic cosmological theory and common observat
 ional techniques such as galaxy surveys and CMB studies. I then provid
 e motivation for the use of HI intensity mapping along with a descript
 ion of how such measurements are performed. I describe my research wor
 k\, in particular the design of an ultra-wideband antenna and the deve
 lopment of foreground cleaning techniques. For the antenna project\, I
  created an ultra-wideband design that was optimized with intensity ma
 pping systematics in mind. This involved the use of a Vivaldi feed wit
 h optimized profile and a deep dish with and an elliptical collar. I a
 lso investigated the use of absorbers\, which helped mitigate systemat
 ics but resulted in significantly lower sensitivity. The final antenna
  design achieved satisfactory levels of spectral smoothness\, impedanc
 e matching and sensitivity to the 21cm hydrogen line. In simulations\,
  I found that my design efforts helped reduce coupling between neighbo
 ring antenna elements\, though not to the level desired. For the foreg
 round cleaning projects\, I investigated the use of Karhunen-Loève tr
 ansforms in both map-space and visibility space. My project was the fi
 rst to incorporate a KL transform in map space. This work however\, di
 d not seem to provide a substantial improvement over other available m
 ethods. I then conclude by discussing my opinions of and ideas for the
  future of HI intensity mapping.
URL:https://www.physics.wisc.edu/events/?id=8825
END:VEVENT
END:VCALENDAR