Speaker
Dr
Giacomo De Angelis
(LNL)
Description
The search for physics beyond the Standard Model (SM) is presently a major issue. Despite its
spectacular success, it is recognized that the SM could be incomplete and could eventually be
incorporated into a more fundamental framework. As an example the excess of matter over
antimatter in the Universe indicates the presence of baryon-number- violating interactions and most
likely of new sources of charge conjugation-parity (CP) violation.
The existence of a finite permanent electric dipole moment (EDM) of a particle or an atom would
violate time-reversal symmetry (T), and would also imply violation of the combined charge
conjugation and parity symmetry (CP) through the CPT theorem [1,2,3]. EDMs are suppressed in
the SM of particle physics, lying many orders of magnitude below current experimental sensitivity.
Additional sources of CP violation are needed to account for baryo-genesis and many theories
beyond the SM, such as supersymmetry [4,5], predict EDMs within experimental reach.
Experimental searches for EDMs have so far yielded no results. The most significant limits have
been set on the EDM of the neutron [6], the electron [7] and on the 199 Hg atom [8], leading to tight
constraints on extensions of the SM [5].
Nuclear structure can strongly amplify the sensitivity of nuclear EDM measurements. In particular
the occurrence of octupole correlations in nuclei lead to closely spaced parity doublets and
considerably larger Schiff moments. Enhancements factor of 10 2 -10 4 have been calculated for nuclei
with octupole deformation [11,12] or soft octupole vibrations [13]. Actinides atoms as Ra and Pa
are among the best candidate in the search for atomic EDM.
These studies are among the objectives of the SPES radioactive ion beam project of INFN. The
SPES Radioactive Ion Beam (RIB) facility at INFN-LNL is presently in the construction phase.
The aim of the SPES project is to provide high intensity and high-quality beams of neutron-
rich nuclei to perform forefront research in nuclear structure, reaction dynamics and
interdisciplinary fields like medical, biological and material sciences. SPES is based on an ISOL
source with an UCx Direct Target able to sustain a power of 10 kW. The primary proton beam
is delivered by a Cyclotron accelerator with an energy of more then 40 MeV and a beam
current of 200 μA. Neutron-rich radioactive ions are produced by Uranium fission at an
expected fission rate in the target of the order of 10 13 fissions per second. The exotic isotopes
are re-accelerated by the ALPI superconducting LINAC at energies of 10A MeV and higher, for
masses in the region of A=130 amu, with an expected rate on the secondary target of 10 7 -10 9
pps. The status and the perspectives of the project will be presented together with the related
detector developments.
[1] I.P. Khriplovich and S.K. Lamoreaux, CP violation without strangeness (Springer, Berlin 1997).
[2] P.G.H. Sandars, Contemp. Phys. 42, 97 (2001)
[3] M. Pospelov and A. Ritz, Ann. Phys. (N.Y.) 318, 119 (2005)
[4] S.M. Barr, Int. J. Mod. Phys. A 8 209 (1993)
[5] K.A. Olive et al. Phys. Rev. D 72 075001 (2005)
[6] C.A. Backer et al., Phys. Rev. Lett. 97, 131801 (2006)
[7] B.C. Regan et al. Phys. Rev. Lett. 88, 071805 ( 2002)
[8] W.C. Griffith et al., Phys. Rev. Lett. 102, 101601 (2009)
[11] N. Auerbach et al., Phys. Rev. Lett. 76, 4316 (1996)
[12] V. Spevak, N. Auerbach, V.V. Flambaum, Phys. Rev. C 56, 1357 (1997)
[13] V.V. Flambaum and V.G. Zelevinsky Phys. Rev. C 68, 035502 (2003)
Primary author
Dr
Giacomo De Angelis
(LNL)
