Mark Halpern, Assistant Professor

B.Sc. (76), Ph.D. (83) M.I.T.

Research Interests

During the past decade we have developed a sensitive differential spectrometer which was used very successfully to measure the spectrum of the microwave cosmic background radiation (CBR) from a sounding rocket. We found a very low level of distortion of the spectrum compared to the best fit Planck spectrum, sharply constraining models of energy release in the universe since the epoch when positron-electron pairs could be created thermally, a few weeks after the initial singularity.

We are currently at work on a project to use this same instrument to search for anisotropy in the CBR. The differential spectrometer will be coupled to a small telescope and carried above most of the earth's atmosphere on a stratospheric balloon (a forty million cubic foot dry cleaner's bag). In the first flight we will arrange the beam pattern to be sensitive to angular scales from one to several degrees.

This experiment will improve our knowledge of density variations in the primordial plasma filling the universe at early epochs and thereby provide important clues for understanding the origin of large scale structure in the distribution of galaxies. Sensitive measurements of this sort will also tell us a lot about the major foreground source in this experiment, our own galaxy.

Selected Publications

"Rocket Measurement of the Cosmic Background Radiation mm-Wave Spectrum", H.P. Gush, M. Halpern and E.H. Wishnow, Phys. Rev. Lett. 65, 5:537 (1990).

"Measurements of the Anisotropy of the Cosmic Background Radiation and Diffuse Galactic Emission at mm and Sub-mm Wavelengths", M. Halpern, R. Benford, S. Meyer, D. Muehlner and R. Weiss, Ap. J. 332:596 (1988).

"Cooled Low-noise Preamplifier for a Bolometer", Review of Scientific Instruments 63, 1, 90 (1992), H.P. Gush, M. Halpern and S. Knotek.