Clover would have been an experiment to measure the polarization of the

Cosmic Microwave Background The cosmic microwave background (CMB, CMBR), or relic radiation, is microwave radiation that fills all space in the observable universe. With a standard optical telescope, the background space between stars and galaxies is almost completely dar ...

. It was approved for funding in late 2004, with the aim of having the full telescope operational by 2009. The project was jointly run by

Cardiff University Cardiff University () is a public research university in Cardiff, Wales. It was established in 1883 as the University College of South Wales and Monmouthshire and became a founding college of the University of Wales in 1893. It was renamed Unive ...

Oxford University The University of Oxford is a collegiate research university in Oxford, England. There is evidence of teaching as early as 1096, making it the oldest university in the English-speaking world and the second-oldest continuously operating u ...

, the

Cavendish Astrophysics Group The Cavendish Astrophysics Group (formerly the Radio Astronomy Group) is based at the Cavendish Laboratory at the University of Cambridge. The group operates all of the telescopes at the Mullard Radio Astronomy Observatory except for the 32m MERL ...

and the

University of Manchester The University of Manchester is a public university, public research university in Manchester, England. The main campus is south of Manchester city centre, Manchester City Centre on Wilmslow Road, Oxford Road. The University of Manchester is c ...

History

The Clover Project was meant to consist of two independent telescopes, one operating at 95

GHz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), often described as being equivalent to one event (or Cycle per second, cycle) per second. The hertz is an SI derived unit whose formal expression in ter ...

with the other operating at both 150 and 225

. Both telescopes were to be sited near the CBI site in the Atacama Desert, Chile. The two telescope receivers would have been large format focal plane arrays of either 100 or 200 bolometric detectors. The aim of the experiment was to measure the B-mode polarization of the

between

multipole A multipole expansion is a mathematical series representing a function that depends on angles—usually the two angles used in the spherical coordinate system (the polar and azimuthal angles) for three-dimensional Euclidean space, \R^3. Multipol ...

s of 20 and 1000 down to a sensitivity limited by the foreground contamination due to lensing. This would have allowed the detection of primordial

gravitational waves Gravitational waves are oscillations of the gravitational field that travel through space at the speed of light; they are generated by the relative motion of gravitating masses. They were proposed by Oliver Heaviside in 1893 and then later by H ...

in the universe so long as the ratio of scalar perturbations (caused by density fluctuations in the early universe) to the tensor perturbations caused by gravitational waves was greater than

r = 0.01

. It was hoped that the telescope would have spent around 2 years observing a total of around 1,000 degrees of sky, made up of several patches of sky where polarized foregrounds (

synchrotron A synchrotron is a particular type of cyclic particle accelerator, descended from the cyclotron, in which the accelerating particle beam travels around a fixed closed-loop path. The strength of the magnetic field which bends the particle beam i ...

and thermal dust emission) are at a minimum. Clover was canceled in March 2009 as STFC were unable to provide the requested additional funds of 2.55 million pounds to finish the project.

History

References

Further reading

Journal articles