Bulletin of the American Physical Society
APS April Meeting 2015
Volume 60, Number 4
Saturday–Tuesday, April 11–14, 2015; Baltimore, Maryland
Session U14: Mini-symposium on Future MeV Gamma-Ray Science and MIssions |
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Sponsoring Units: DAP Chair: Jeremy Perkins, NASA/GSFC Room: Key 10 |
Monday, April 13, 2015 3:30PM - 4:06PM |
U14.00001: Science from the MeV Gamma Ray Sky Invited Speaker: Reshmi Mukherjee Typically, MeV gamma-ray astronomy has been more technically challenging compared to other energy regimes in gamma-ray astronomy. However, the motivation for MeV gamma-ray astronomy remains compelling. In this talk we will review the astrophysics results from the gamma-ray sky in the 10-100 MeV band and discuss the science cases for an MeV mission in the light of recent scientific results from ground-based very high energy (VHE) instruments, as well as Fermi, NuSTAR, and Swift. [Preview Abstract] |
Monday, April 13, 2015 4:06PM - 4:18PM |
U14.00002: Scientific Optimization for Proposed MeV Gamma-Ray Instruments, Lessons Learned From the Fermi-LAT Eric Charles Designing a gamma-ray telescope to operate in the MeV range will inevitably require making hard choices when it comes to optimizing the instrumental performance. In particular, the choice of available detector technologies combined with the limited space and power available to space-based missions suggest that trade-offs between the collecting area, the field of view, and the spatial and spectral resolution will be required. In this contribution I will summarize some lessons learned from the performance optimization of the Fermi-LAT, and discuss how they may be applicable to proposed MeV instruments. [Preview Abstract] |
Monday, April 13, 2015 4:18PM - 4:30PM |
U14.00003: Next Generation Compton Telescope Design Challenges Bernard F. Phlips, J. Eric Grove, W. Neil Johnson, Richard S. Woolf, Eric A. Wulf The next generation Compton telescope faces many challenges in achieving the desired sensitivity in the 1-10 MeV energy band. Fine spectral and imaging performance point to the use of semiconducting detectors. Practical issues point to the use of scintillation detectors. We will discuss positive developments and disappointments encountered over the last few years of Compton Telescope development at NRL. [Preview Abstract] |
Monday, April 13, 2015 4:30PM - 4:42PM |
U14.00004: Extending Fermi LAT discoveries: Compton-Pair Production Space Telescope (ComPair) for MeV Gamma-ray Astronomy Alexander Moiseev, Elizabeth Hays, John Mitchell, Julie McEnery, Jeremy Perkins, David Thompson The gamma-ray energy range from a few hundred keV to a few hundred MeV has remained largely unexplored, mainly due to the challenging nature of the measurements, since the pioneering, but limited, observations by COMPTEL on the Compton Gamma-Ray Observatory (1991-2000). This energy range is a transition region between thermal and nonthermal processes, and accurate measurements are critical for answering a broad range of astrophysical questions. We are developing a MIDEX-scale wide-aperture discovery mission, ComPair (Compton-Pair Production Space Telescope), to investigate the energy range from $\sim$ 300 keV to 1-10 GeV with high energy and angular resolution and with sensitivity approaching a factor of 100 better than COMPTEL. This instrument will be equally capable to detect both Compton-scattering events at lower energy and pair-production events at higher energy. ComPair will build on the heritage of successful space missions including Fermi LAT, AGILE and PAMELA, and will utilize well-developed space-qualified detector technologies including silicon strip detectors, heavy inorganic scintillators, and plastic scintillators. [Preview Abstract] |
Monday, April 13, 2015 4:42PM - 4:54PM |
U14.00005: The Future of High Energy Polarimetry Mark McConnell In recent years there has been a steadily increasing interest in exploiting polarimetry as a new tool in gamma-ray astronomy. Gamma ray polarization can be measured by exploiting the characteristics of each interaction mechanism that is used to measure high energy photons: the photoelectric effect, Compton scattering, and pair production. We will review each of these methods and summarize the experimental efforts to date. During the past 10 years there have been several reports of polarization from gamma ray bursts (GRBs), along with reports of gamma ray polarization from both the Crab Nebula and Cygnus X-1. Although of limited statistical significance, these results provide a tantalizing glimpse of the potential for such measurements. We will then provide a summary of current efforts to measure gamma ray polarization and discuss polarimetry as an important capability for future gamma ray missions. [Preview Abstract] |
Monday, April 13, 2015 4:54PM - 5:06PM |
U14.00006: Advanced Energetic Pair Telescope (AdEPT), a Medium-Energy Gamma-Ray Polarimeter Stanley Hunter Since the launch of AGILE and FERMI, the scientific progress in high-energy ($\mathrm{E}_{\gamma }>200\thinspace \mathrm{MeV})$ gamma-ray science has been dramatic. Both of these telescopes cover a broad energy range from about $\sim 20$ MeV to $>10$ GeV. However, a significant sensitivity gap remains in the medium-energy regime (0.75 -- 200 MeV) that has been explored only by COMPTEL and EGRET on CGRO. Exploring this regime with angular resolution near the kinematic limit and high polarization sensitivity requires a telescope design with a low density electron track imaging detector. The medium-energy ($\sim $5 to 200 MeV) Advanced Energetic Pair Telescope (AdEPT), will achieve angular resolution of $\sim $0.6 deg at 70 MeV, similar to the angular resolution of Fermi/LAT at $\sim 1$ GeV. AdEPT will also provide unprecedented polarization sensitivity of $\sim 1\% $ for a 1 Crab source. The enabling technology for AdEPT is the Three-Dimensional Track Imager (3-DTI) a low-density, large volume, gas time-projection chamber with a 2-dimensional readout. We describe our ROSES/APRA funded program to build a 50x50x100 cm3 AdEPT prototype, measure the angular resolution and polarization sensitivity of this prototype at an accelerator. [Preview Abstract] |
Monday, April 13, 2015 5:06PM - 5:18PM |
U14.00007: Unique Perspective of High-energy Astrophysical Systems Offered by Future MeV Polarization Observations Tonia Venters Polarization measurements at MeV energies would provide a complementary probe into the nature of high-energy astrophysical sources. For instance, polarization measurements would provide a diagnostic for distinguishing among various emission models in gamma-ray sources such as supernova remnants, blazars, GRBs, and starburst galaxies. Polarization measurements will also provide the capability to probe jet geometries and magnetic fields in high-energy astrophysical sources. In this talk, I will discuss examples of the science space that would be opened up by performing polarization measurements at MeV energies. [Preview Abstract] |
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