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LSPE : the Large-Scale Polarization Explorer

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 the target :

LSPE is a mm-wave polarimeter aboard of a stratospheric balloon, aimed at measuring the polarization of the Cosmic Microwave Background at large angular scales.

Small inhomogeneities of the primeval plasma, at the epoch of the last scattering (13.7Gy ago, 380ky after the big bang), induce a small degree of linear polarization in the CMB (E-modes). 

Gravitational waves produced during inflation, a split-second after the big-bang, also induce linear polarization in the CMB (both E-modes and B-modes).

Measuring CMB polarization with high precision one can study the very early universe and the inflation process, happening at energies (>1016 GeV) which cannot be reproduced in the laboratory.

The signal from B-modes is extremely small, < 0.1 mK rms and is mainly at large angular scales. LSPE targets are the reionization bump and the recombination bump in the angular power spectrum of B-modes.

Launch of a 800000 m3 stratospheric balloon from the airport of Longyearbyen (Svalbard). The circumpolar flight, at around 37 km of altitude, can be 2 weeks long.



  the instruments :

The Large-Scale Polarization Explorer is
- a stratospheric balloon payload,
SWIPE , flying long-duration in the polar night
- spinning to cover a large fraction of the sky (
20-25% per flight)
- aiming at CMB polarization at large angular scales
- using polarization modulators to achieve high stability
- using multi-mode bolometers for extreme sensitivty
- Frequency coverage of SWIPE: 120 – 250 GHz (3 channels)
- Angular resolution: 1.3o FWHM
- a ground based instrument,
STRIP , operated in Tenerife, using coherent radiometers
Frequency coverage of STRIP: 40 – 90 GHz (2 channels)
- Angular resolution: 0.5o FWHM
- Combined sensitivity: 20 mK arcmin per survey (1y)
- sky coverage overlapping the SWIPE one.

Left: Preliminary sketch of the LSPE-SWIPE payload, without thermal protections. The total mass is around 2 tons, the overall dimensions are 1.8m(w) x 3.8m(d) x 4.0m (h). A 800000 m3 balloon is used to lift the instrument at 38 km of altitude.

contacts :

Prof. Paolo de Bernardis 

Dipartimento di Fisica, Sapienza Università di Roma

P.le A. Moro 2, 00185 Roma, Italy

Tel.: +39 06 49914271 - Fax: +39 06 4957697 - paolo.debernardis at

news :

The LSPE instrument is funded by ASI and INFN and is in preparation.
The SWIPE payload will be flown from Longyearbyen (Svalbard) in a long duration winter flight. The STRIP instrument will be installed in Tenerife.


                                                     last update :  May. 28th, 2017