MAX, MAXIMA, & BOOMERANG
MAX (Millimeter Anisotropy eXperiment) and its next generation MAXIMA
(MAX IMaging Array) and BOOMERANG are balloon-borne, bolometric instruments
designed to measure the cosmic microwave background anisotropy
on angular scales of degrees to less than a degree.
MAX was and MAXIMA and BOOMERANG are part of the NSF Center for Particle Astrophysics.
The purpose of MAX, MAXIMA and BOOMEANG is to measure and eventually to map
cosmic microwave background (CMB) anisotropies on the sub-degree angular
scale level. This is a significantly smaller angular scale than
COBE (>7 degrees) observations. This angular scale is expected to
contain Doppler peaks in the average level of fluctuations since
not only do the primordial density fluctuations contribute but on this
smaller angular scale some of the primordial density fluctuations can
have just collapsed carrying the CMB photons with them. This creates
additional sources of anisotropy caused both by the condensing (compression)
of photons with the matter and by the motion. The peak in fluctuations
is expected to be near to one degree on the sky, if the Universe has a
flat geometry and on smaller angular scales if the Universe is open.
MAXIMA and BOOMERANG will also be able to check the statistical properties of the fluctuations to determine if they are Gaussian as expected
for inflationary big bang models or more non-Gaussian as expected
from topological defect theory.
MAX is a balloon-borne, bolometric instrument that has had 5 flights to date.
We are currently preparing for a sixth flight. This time we plan to utilize
the new primary mirror that was purchased for the up grade to MAXIMA.
For the first 5 flights MAX utilized a 1.2-meter diameter off-axis parabola
and a chopping secondary.
[Insert figure showing diagram of MAX]
The MAX receiver a four bolometer photometer operating at frequencies
of 3.5, 6, 9 and 14 cm^-1 (number of waves per centimeter or
wavelengths of 2.9, 1.7, 1.1, and 0.7 mm respectively).
The reciever was improved and altered during the flights to lower
temperatures first via a He3 refridgerator operating at 0.3K and
then with an ADR (adiabatic demagnitization refridgerator) operating
Click here or alternately
here to get a list of MAX publications.
to the MAX data.
MAXIMA is the upgrade of the MAX concept to an array for making images
of sections of the sky with an angular resolution of about one fifth
of a degree (~12').
MAXIMA utilizes a 1.5-m diameter light-weight chopping primary.
MAXIMA is projected to have 14 pixels.
For its first flight these will be single frequency-band bolometers
but it can handle 4-frequency-channel bolometer assemblies the MAX type.
Drawing of MAXIMA gondola with the single-pixel MAX receiver used in the
September 1996 flight.
The "inner frame" holds the primary mirror, secondary optics, and the cryostat.
This inner frame tilts with respect to the outer frame to point the beam in
The bottom of the gondola has a pallet constructed with aluminum honeycomb,
which is very light and strong.
The structrural members are made of 3 inch wide aluminum angle.
A simplified version of the flywheel system used to point the gondola in
azimuth can be seen at the top of the gondola.
The entire gondola will weigh about 2,500 lbs.
schematic in configuration for August 1997 flight.
This shows the larger cryostat for the array receiver.
Schematic of the MAXIMA receiver showing the cold optics:
It also shows the three cryogenic stages of the five temperature ranges:
Ambient temperature exterior - well below freezing during flight
Liquid nitrogen (77 K) shield
Liquid Helium-4 (4 K at STP, ~2 K at high altitude) shield
Liquid Helium-3 (0.3 K)
Adiabatic Demagnetization Refridgerator (<0.1 K)
The prime focus shown is from the primary mirror.
The primary mirror is very light weight - about 12 kilograms
and can be kept stationary, oscillate, or make a roughly triangular
with time angular scan on the sky.
For the next flight the mirror will make a 4-degree peak-to-peak scan.
The entire optics are enclosed in a large shield.
Cold secondary and terciary mirrors allowa cold baffle to be
placed at at the optimum spot in the optical path.
This baffle rejects millimeter-wave radiation from outside the desired beam
An Adiabatic Demagnetization (ADR) will cool the photometers to 100 mK, and
a pumped Helium-three stage will provide an intermediate
temperature of 300 mK.
Cryostat & Receiver in another potential configuration.
Drawing of MAXIMA cryostat and receiver of a version that contains
an array of 8 photometers (seen toward left of drawing).
Each photometer will have four separate frequency channels and
will look at a 20-arcmin wide circular pixel on the sky. Ray tracings are
visible in this drawing show the optical path from the entrance
of the cryostat to the entrances of the photometer light pipes..
Showing the bolometer detector assembly, feed horns, and cold plate
of the cryostat.
detail of the detector assembly and feed horns.
Figure showing the expected beam pattern on the sky for
(a) BOOMERANG northern hemisphere flight in spring 1997.
The goal is to use the bolometers in total power mode
taking advantage of the specially developed electronics.
However, each bolometer has a matching partner, at either 2.8, 3.5, or 4
degrees separation so that differences between the members of the pair
(electronically and digitally) will provide back up information
on smaller angular scale.
The scan strategy is to point the bolometers at roughl 45-degrees elevation
and then rotating the gondola in azimuth at roughly 1 rpm
which will trace out a circle on the sky.
the rotation of the Earth then sweeps that circle on the sky
providing coverage of about 25% of the northern hemisphere
on one night's flight.
(b) MAXIMA summer 1997 flight configuration
The MAXIMA beams are closely packed and are scanned rapidly
by the wiggling primary and slowly with azimuth scans of the gondola.
The plan for the first flight is to guide using Polaris
and scan at high angular resolution
a small region in a low dust region near the north pole.
(c) BOOMERANG circum-polar flight in December 1998
The BOOMERANG long duration balloon flight is designed to have
higher angular resolution than the northern flight but similar
separation in the case atmospheric noise and stability are
insufficient for the total power mode.
List of MAXIMA/BOOMERANG collaborators
institutions/positions and responsitibilities.
Photographs of flight preparations and launch of MAXIMA-0
in September 1995.
Expected sensitivity for measuring CMB anisotropy power spectrum
for the three planned flights.
BOOMERANG is the upgrade of the MAX concept to an array for making images
of sections of the sky from Long Duration Balloon (LDB) flights.
For more information consult the
BOOMERANG home page.
Documentation on MAXIMA
is available as are the data products for MAX.
Further information is available on the
CfPA web server on the
Cosmic Microwave Background research page.
Return to the Smoot Group page
for a complete description of Dr. Smoot's group's research activities.
Revised 27 August 1996; email@example.com