Nanostructures, such a quantum dots or nanoparticles, made of three-dimensional
topological insulators (3DTIs) [1-5] have been recently attracting increasing interest,
especially for their optical properties. We present results for the energy spectrum,
the surface states and the dipole matrix elements for optical transitions with in-
plane polarisation of 3DTI nanowires of finite height L and radius R. We first derive
an effective 2D Hamiltonian by exploiting the cylindrical symmetry of the problem.
We develop two approaches: The first one is an exact numerical tight-binding model
obtained by discretising the Hamiltonian; The second one, which allows us to obtain
analytical results, is an approximated model based on a large-R expansion and on
an effective boundary condition to account for the finite height of the nanowire.
We find that the agreement between the two models, as far as eigenenergies and
eigenfunctions are concerned, is excellent for the lowest absolute value of the
longitudinal component of the angular momentum. Finally, we derive analytical
expressions for the dipole matrix elements by first considering the lateral surface
alone and the bases alone, and then for the whole nanowire. In particular, we focus
on the two limiting cases of tall and squat nanowires. The latter case is compared
with the numerical results finding a good agreement

Titolo
Dall'immagine diagnostica al paziente: evoluzione di un trattamento BNCT

Relatori
I.Postuma, B.Marcaccio, S.Fatemi

Ai confini dell’indivisibile.

Relatori: C.Aimè, D.Rebuzzi, A.Negri

Titolo
Particelle elementari e interazioni fondamentali.

Relatori
E.Budassi, C.Del Pio, A.Gurgone

Titolo
Un nettare per curare l’Alzheimer: la fisica nucleare in soccorso
all’invecchiamento globale.

Relatori
N.Protti, V.Pascali

Titolo
Una proposta per l'insegnamento della meccanica quantistica.

Relatore
G.Introzzi

Titolo
SUPERQUARK: viaggio al centro del nucleo.

Relatori
S.Venturini, M.Cerutti, L.Rossi

Titolo
Quantum computing. Dagli algoritmi all'intelligenza artificiale: sfide e promesse di una tecnologia emergente.

Relatori
F.Scala, S.Roncallo

The Beam Dump eXperiment is a state of the art, modern beam dump experiment approved by JLab PAC with maximum scientific rate. BDX aims to detect light dark matter particles in the interaction of the intense 11 GeV CEBAF electron beam with the dump of experimental Hall-A. In this contribution I will show the genesis of the experiment and its evolution  toward a pilot run we just concluded at Jlab (BDX-MINI). The physics case, as well as the experimental technique (simulation framework, detector design and prototyping), will be review and discussed.
 

Many astrophysical observations as well as anomalies in processes involving electromagnetic currents (e.g. the muon anomalous magnetic moment) could be reconciled assuming the existence of a new kind of matter, not directly interacting with light, called Dark Matter (DM). While gravitational effects of DM are quite well established, despite the tremendous efforts being devoted to reveal the nature of DM in terms of new elementary particles, no clear results have been obtained so far. Many experimental efforts are dedicated to direct detection of galactic DM, as well as to study the indirect effects of its presence. Due to the lack of results by ‘traditional’ DM searches, in the last few years the experimental activity extended to search for hints of DM produced at accelerators. Technological advances allow nowadays running high intensity  beams of moderate energy well suited for these studies. According to some theories beyond the Standard Model (SM) Light Dark Matter (LDM ) (1-1000 MeV) can interact with SM matter via a new force, mediated by a heavy vector boson called A’ or ‘heavy photon’. Depending on the relative masses of the A’ and the DM particles, the A’ can decay to SM particles (‘visible’ decay) and/or to light DM states (‘invisible’ decay). In this talk, I will give an overview of the LDM physics, focusing on the current experimental effort in the field.