banner image
No data available.
Please log in to see this content.
You have no subscription access to this content.
No metrics data to plot.
The attempt to load metrics for this article has failed.
The attempt to plot a graph for these metrics has failed.
MAXIMA: A balloon-borne cosmic microwave background anisotropy experiment
Rent this article for


Image of FIG. 1.
FIG. 1.

(Color online) The MAXIMA power spectrum of the CMB computed using a hybrid analysis of resolution (up to ) and resolution (over ) maps. is the spherical harmonic multipole principal quantum number. is the power spectrum of angular fluctuations. is the total power per logarithmic interval in . The first peak in the power spectrum is a powerful probe of the total energy density of the universe (Refs. 3–6). Error bars show one standard deviation statistical uncertainties. The solid curve is the power spectrum of the best fit model from Ref. 5 with , , , , and . The crosses are the power spectrum of the difference between the map from one detector and the combined map from the other two detectors used for the analysis (Ref. 2) It is consistent with zero.

Image of FIG. 2.
FIG. 2.

A drawing of the MAXIMA telescope from an elevated front/side perspective. Rays representing the telescope beam are shown reflecting from the primary mirror into the cryogenic receiver. Electronics housed in the rectangular boxes on the sides of the instrument include the pointing system, data multiplexers and digitizers, and telemetry and command interfaces. Near the top of the telescope were motors controlling azimuthal orientation. The inner frame consisting of the primary mirror and the receiver was tilted relative to the outer frame to change the telescope elevation. The gondola frame was covered in lightweight aluminum-covered builders foam (not shown) and the primary mirror is surrounded by a scoop built of aluminum sheet (not shown), both of which shielded the telescope and receiver from stray optical and radio frequency radiation.

Image of FIG. 3.
FIG. 3.

(Color online) The MAXIMA telescope hanging from the launch vehicle shortly before the MAXIMA II flight on 16 June 1999.

Image of FIG. 4.
FIG. 4.

(Color online) The MAXIMA I CMB observation scan (white) is plotted over emissions from galactic dust taken from the Berkeley-Durham IRAS-Dirbe map of the northern galactic hemisphere dust emission extrapolated to (Ref. 46). Areas of the sky with low dust emission appear as dark regions of the map. The MAXIMA I CMB observation region is constrained to .

Image of FIG. 5.
FIG. 5.

(Color online) The reconstructed pointing for a single detector in both MAXIMA flights. MAXIMA I is the lighter region on the right, and MAXIMA II is the darker region on the left. The scan region for each flight is boxed, and the overlap region can be seen at right ascension .

Image of FIG. 6.
FIG. 6.

(Color online) Left: The telescope was a fast Gregorian system. The primary mirror, a diameter underilluminated paraboloid, was modulated about the indicated axis. A Winston cone baffle (shown outside the cryostat window) blocked radiation not arriving from the primary mirror. Cooled secondary and tertiary mirrors corrected aberrations from the primary and reimaged the focal plane on an array of feedhorns which channeled light to the bolometers. The upper portion of the cryostat housed the cooling systems. Right: The focal plane was baffled from stray light in several ways. At least five edge diffractions with angles of up to 65° were required for rays outside of the defined throughput to arrive to the focal plane. The internal baffles were blackened with millimeter wave absorptive material and the Winston cone baffle restricted the throughput to radiation from the primary mirror. A Lyot stop defined the illumination on the primary mirror. Filters which defined the measurement bands were located at the prime focus near the cryostat window, at the Lyot stop, and after the feedhorns.

Image of FIG. 7.
FIG. 7.

(Color online) The layout of the MAXIMA focal plane as viewed from behind the bolometers. The arrows indicate the scan direction for azimuthal modulation at constant elevation. All 16 channels project onto the sky with a FWHM beam size. The width of the focal plane was .

Image of FIG. 8.
FIG. 8.

(Color online) A photograph of the arrays of feedhorns and bolometers. The entrances of the feedhorns at the bottom defined the curved focal surface. The band defining metal-mesh filters and bolometers for each channel were assembled inside aluminum holders at the top. The horn array at and the bolometer array at were separated by a gap. The cold bolometer-filter stage was supported by three thin walled Vespel SP-22 tubes.

Image of FIG. 9.
FIG. 9.

The measured, normalized spectral response for one detector of each color. These spectra were measured before flight with a Michelson Fourier spectrometer. The solid curve represents the derivative of the emission spectrum of a blackbody with respect to temperature .

Image of FIG. 10.
FIG. 10.

Beam contour plots for all channels, shown in the reverse of the view in Fig. 7. Left: MAXIMA I: the contours, starting at the center of each beam, represent the 90%, 70%, 50%, and 30%, levels, respectively. Right: MAXIMA II: The contours represent the 90%, 70%, 50%, 30%, and 10%, levels, respectively. Two of the channels were not operational during the MAXIMA II flight. Refinements in focusing techniques between the MAXIMA flights led to improved beam symmetry in MAXIMA II.

Image of FIG. 11.
FIG. 11.

Data from preflight sidelobe tests. The source was roughly from the telescope. Left top: Test data in the elevation direction for MAXIMA I. The angle was that of the telescope above the test source. Right top: Test data in the azimuth direction for MAXIMA I. The telescope was rotated at fixed elevation . Left Bottom: As above, for MAXIMA II. Most of these data were collected with the source at higher elevation than the telescope beam (negative angles on the axis). Right bottom: As above, for MAXIMA II, except that the source was moved around the telescope.

Image of FIG. 12.
FIG. 12.

The bolometer pictured is of the same design as those used in MAXIMA. The spider-web absorber had a diameter with a 5% filling factor. The radial components within the spider-web pattern were long and wide. The NTD-Ge thermistor, a rectangle with sides, was bump bonded to the center of the web. The chip was powered through two lithographed gold leads. Mechanical support came from the electrical leads and 16 silicon nitride legs, long and wide. Photograph courtesy of Bock.

Image of FIG. 13.
FIG. 13.

Bolometer noise simulation. The top panel is a plot of the contributions to the bolometer NEP as a function of the ratio of the electrical power to the optical power . The contributions are thermal fluctuation noise (dot-dash), Johnson noise (circles), amplifier noise (crosses), and photon noise (dotted). The solid line is the quadrature sum of the terms. The bottom panel is a plot of the thermistor temperature as a function of the same ratio of powers. We show the simulation for an operating temperature of , an optical load of , an average thermal conductance of , and JFET voltage noise of .

Image of FIG. 14.
FIG. 14.

The measured noise equivalent power (NEP) as a function of audio frequency for a MAXIMA bolometer plotted along with theoretical NEP contributions from photon (dotted), Johnson (long dash), thermal fluctuation (short dash), and amplifier (dot-dash) noise. The total NEP (solid line) is the quadrature sum of the terms. It was believed that the low frequency noise below arises from temperature drifts in the cryogenic system. Electronic filters in the readout circuit cause the signal to roll off above

Image of FIG. 15.
FIG. 15.

The bolometers (shown with resistor symbols) were shielded from electrical RFI by three different types of filters in series, shown as filled rectangles. RFI was prevented from transmitting coaxially between the temperature baffles by contiguous layers of aluminized Mylar placed around the optical path at the cryostat window. The cryostat and the warm electronics shield acted as Faraday cages.

Image of FIG. 16.
FIG. 16.

MAXIMA II dipole data and fit. Top panel: The top trace is the data from a bolometer during observations of the CMB dipole. An overall gradient is removed and the offset is arbitrary. The sinusoidal signal is the CMB dipole modulated by the rotation of the telescope ( period). The large spikes were caused by emissions from dust near the galactic plane. The lower trace is a fitted model curve, including the CMB dipole and a galactic dust map. Bottom panel: The difference between the model and the fit in the top panel is shown. The pointing accuracy was not good enough to model the data from the galactic plane accurately. These regions were not included in the fit.

Image of FIG. 17.
FIG. 17.

Temperature dependence of the responsivity of a detector. These data were collected during MAXIMA II. The point near , measured shortly after sunrise, showed less responsivity than would be expected from the nighttime data because of the higher radiation loading. During MAXIMA I, the temperature of the thermal reservoir only varied from .

Image of FIG. 18.
FIG. 18.

(Color online) Two motors near the top of the telescope controlled the azimuthal orientation by driving against a reaction wheel and the cables from the balloon, respectively. A linear actuator and servoarm tilted the inner assembly, pointing the telescope in elevation. A motor below the primary mirror modulated it at relatively high speed (, amplitude) in azimuth. The frames shown on the front and back of the telescope were baffled to reduce far sidelobe response.

Image of FIG. 19.
FIG. 19.

A simulation of the double modulation in azimuth. The axis is the azimuthal position of the telescope beams, while the axis is time. The slower modulation was caused by the motion of the entire telescope, while the faster modulation was caused by the rotation of the primary mirror about the optic axis.

Image of FIG. 20.
FIG. 20.

A MAXIMA II scan pattern plotted in RA and declination, combining the azimuthal modulations with the rotation of the sky. Lines of constant elevation span the plot in an arc from the lower left to the upper right and move with the rotation of the sky. The gaps seen in this scan pattern are less than half the telescope beam width.

Image of FIG. 21.
FIG. 21.

The cross-linked scan pattern from MAXIMA II, consisting of two scans similar to that shown in Fig. 20. The average cross-linking angle was 27°.


Generic image for table
Table I.

Flight statistics.

Generic image for table
Table II.

Optical parameters of the MAXIMA telescope.

Generic image for table
Table III.

Predicted optical load during flight.

Generic image for table
Table IV.

Optical efficiencies for the MAXIMA receiver.

Generic image for table
Table V.

MAXIMA beams FWHM. Note that and represent the major and minor axes. Values were determined from the 50% contour for each beam. M1 and M2 refer to MAXIMA I and MAXIMA II.

Generic image for table
Table VI.

Sources of beam error for one channel.

Generic image for table
Table VII.

Average bolometer thermal properties.

Generic image for table
Table VIII.

MAXIMA I bolometer characterization. Note that data from the channels in bold were used for Ref. 1, 2, and 5 data analysis.

Generic image for table
Table IX.

MAXIMA II bolometer characterization. Note that data from the channels in bold were used for Ref. 4 and 42 data analysis.

Generic image for table
Table X.

MAXIMA cryogenic systems. Note that numbers are quoted for flight conditions.

Generic image for table
Table XI.

Calibration linearity. Note that quoted values were derived from the maximum of the signal for MAXIMA I (before the slash) and MAXIMA II (after the slash). Ranges represent variations between detectors. For the dipole calibration the upper limit on nonlinearity was .

Generic image for table
Table XII.

Pointing performance.

Generic image for table
Table XIII.

Pointing reconstruction uncertainties.


Article metrics loading...


Full text loading...

This is a required field
Please enter a valid email address
752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: MAXIMA: A balloon-borne cosmic microwave background anisotropy experiment