RUB Research School

Detail

  1. Sie sind hier:
  2. Startseite
  3. Über uns
  4. Map of International Research Activities (MIRA)
  5. Detail
Back

Author
Name Krieger, Niclas
Research field Cosmic Rays
Career stage doctoral researcher
Home university/institution Ruhr-Universität Bochum (RUB)
Department/Research unit at home university/institution Physics and Astronomy
Chair/Working group at home institution Theoretical Physiscs IV

International activity
Country United States
Location Madison, Wisconsin
University University of Wisconsin-Madison
Fund Non Research School
Type of activity research stay
Period starts 04-09-2024
ends 09-11-2024
Keywords Cosmic Rays, IceCube Neutrino Detector, Heliophysics, Astroparticle Physics
Report Cosmic Rays (CRs) are high-energy charged particles, primarily protons and other atomic nuclei, that travel through the Universe. CRs originate from various sources in the Universe e.g. from distant galaxies.
On their way to Earth, CRs are blocked by celestial objects, e.g. the Moon, resulting in a relative deficit of detectable CRs at Earth.
Since CRs are charged particles, they get deflected by magnetic fields.
The Sun has its own magnetic field, the so-called Solar Magnetic Field (SMF), that causes not only blocking of CRs but deflection as well when propagting close to the Sun and leaving its footprint in the CRs since the SMF directs those on various tracks. This enables an indirect measurement of the Sun's magnetic field with the CRs that are only slightly deflected and therefore still detectable at Earth.
Both objects will lead to less detectable CRs, a relative deficit, that is called a Shadow.

CRs can be detected by atmospheric muons, secondary charged particles that are the result of the intercation between CRs and air molecules in Earth's atmosphere.
The IceCube Neutrino Detector that is located at the South Pole is able to detect those muons. Even if IceCube's primary goal is the detection of high-energy neutrinos from astrophysical sources, it can also be used for the detection of CRs.
The main detector is imbedded in the clear Antarctic ice, has an instrumental volume of one cubic kilometer and composes of 86 strings that carry over 5000 light detectors.
When secondary charged particles, for example atmospheric muons, travel through the ice, a small amount of light is generated that can be measured. By detecting this light, the track of the particle, a muon for instance, can be estimated from the occuring pattern and the direction as well as the energy of the muon can be determined.

My project is the continuation of the previous analysis that uses IceCube data in order to obtain the Shadows for the Sun/Moon for each year. With the Moon Shadow, different reconstruction methods can be tested and improved.
By using the Sun Shadow, comparisons to different Coronal Magnetic Field Models are possible what will help understanding the SMF better. Furthermore the dependence on the Solar cycle as well as Sunspot number can be estimated.

On December the 24th of 2024 the Parker Solar Probe did its closest approach to the Sun, coming to a distance of 6.1 million kilometers from the surface. This is the closest a probe has ever been to the Sun's surface.
With the help of this data, we are hoping to get valuable information about the Sun's outer Corona and to get a comparison between this direct measurement and the indirect measurement with the Sun Shadows.

During my stay in Madison, I worked on the Shadow filters that are used for the event selection for the upcoming analysis since an event is only selected for the analysis if it fulfills certain criteria. Furthermore I wrote and/or updated the programs for the analysis that are used to generate the Shadows. In order to start the analysis, the data needs to be processed. For this, different steps are needed until the data has the level that will be used in the analysis. Here, I worked on the last two steps of the finalization of the data that use so-called Quality cuts.

Assistant Research Professor Dr. Paolo Desiati was part of the previous Shadow analysis. For this I visited him at the University of Wisconsin-Madison for 8 weeks from the beginning of September to the beginning of November 2024.
The University of Wisconsin-Madison is the leading institution in the IceCube Collaboration of which RUB is a member as well. Dr. Paolo Desiati and his colleagues were able to provide me with knowledge about the previous analysis and helpful discussions about the event selection as well as about the physics.
During my stay, the IceCube Fall Collaboration Meeting took place in Madison which was a good opportunity to get in contact with all the members of the Collaboration to discuss open questions and interesting points about the analysis but also to present the current status of my work.
Back