GRUPPO III

Attività di Fisica e Astrofisica Nucleare

Composizione Esperimenti Attività sperimentale e teorica recente Attività sperimentale e teorica 2011 Richieste Pubblicazioni (Commento sui giovanissimi: Guerro, Trippella, Madaffari)

Composizione del Gruppo III-PG

FTE=9

GAMMA. GAMMA performs nuclear structure studies using existing instrumentation like CLARA, RISING and GASP and takes part actively to the development of instrumentation for gamma-ray spectroscopy within AGATA. The physics program includes the following topics: • Shell structure in n-rich nuclei (CLARA, RISING); • Isospin symmetries and n-p pairing (GASP, CLARA, RISING); • Pigmy resonance of interest in astrophysics (CLARA, RISING); • Structure of nuclei at the proton-drip line (GASP); • Critical points and phase transitions between different nuclear shapes (GASP). • Within the AGATA project: Gamma-ray tracking in HPGe segmented etectors.

Aerial view of the PRISMA+CLARA setup

View of RISING + HECTOR

GASP Conf.I coupled to the n-Ring

Pictorial view Of the AGATA array

Coordinator for Perugia, up to 2009: Gianni Lo Bianco.

When Gianni died, idea of closing the group working to the experiment In Camerino.

Recently: decision to go on for next couple of years to finish the ongoing experiments involving PHD students from PG-Camerino.

ERNA. A European collaboration (Italy, Germany, Ungary, Spain) for measuring (and verifying in stellar models) reaction rates of thermonuclear fusion processes at low energies (a few tens of KeV) of relevance in stellar astrophysics.

When the background suppression provided by underground laboratories is not available, one can look for other solutions to make measurements of extremely low rates effective. One of them is to associate a modern mass spectrometer (recoil separator) to an accelerator (in this case the 3 MV tandem in the CIRCE laboratory of Caserta).

Another way of controlling the uncertainties is to operate in INVERSE KINEMATICS, i.e. using and light-nuclei target and heavier-nuclei beams.

ERNA exploits both techniques.

Experiment successfully operated in Bochum in the first decade of XXIst century. Main result: the revision of the 3He+4He reaction rate for solar physics, prediction of neutrino fluxes, 3He consumption in the Universe (Di Leva et al. 2009, Phys Rev. Lett. 102, 2502; Phys. Rev. Lett. 103, 9903).

Then instrument moved to Caserta. 2009 - 2010: support from INFN for re-commissioning in Caserta. Inclusion of the Perugia INFN section as a full partner.

2011: first measurements in Caserta.

1.7Be(p,g)8B2 4He. Solar physics, neutrinos, Low Mass Star nucleosynthesis

2. 12C(a,g)16O Massive star evolution and nucleosynthesis, SNe

3. 12C + 12C fusion. Advanced stages of massive star evolution, explosive nucleosynthesis

E ~ kT

nuclear well

V

r rn

T ~ 15x106 K⇒E = kT ~ 1 keV EC = 550 keV

during quiescent burnings: kT << Ec reactions occur through TUNNEL EFFECT

projectile

EC ~ z1z2

z1 z2 Example z1=p and z2=p (e.g. in the Sun)

Maxwell-Boltzmann distribution

Tunneling through Coulomb barrier

Gamow peak

reaction Coulomb barrier (keV)

E0 (keV)

p + p 550 5.9 α + 12C 3430 56

16O + 16O 14070 237

Experimental problems

Er

non resonant process

interaction energy E

extrapolation direct measurement

0

S(E)

LINEAR SCALE

S(E)

-FA

CTO

R

-Er

sub-

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d

reso

nanc

e

low-energy tail of broad resonance

CRO

SS S

ECTI

ON

LOG SCALE

⇓ direct measurements

E0

Ecoul

σ(E)

non-resonant

resonance

extrapolation needed !

man

y or

ders

of

mag

nitu

de

ACTIVITY 2009 - 2010 GAMMA. Experimental activity dedicated to measuring E0 transition in heavy nuclei near the proton-drip line [Mainly 156Dy, 160Er] +hw development (electron spectrometer at LNS (applications :nuclear structure – nucleosynthesis of p processes)

ERNA. Trasportation, then re-commissioning of the recoil separator in Caserta (from Bochum). Preliminary tests with 7Be beams on the windowless H target.

Perugia group: 1) hw developments (GAMMA spectrom.; ERNA: DE-E spectrometer). 2) Theory (preparation of computer codes for stellar Li nucleos. re-calculation – (Palmerini PHD + Busso-Nucci) 3) Observational tests (data acquisition & analysis - Maiorca: Master degree + Start of PHD work; in collab. w. Florence)

ACTIVITY 2011 - Experimental

GAMMA. Experimental activity dedicated to measuring E0 transition in heavy nuclei near the proton-drip line [mainly 162Yb, 164Yb] (nucl. structure – nucleosynthesis of p processes)

ERNA. Start of the new measurements. Two processes with beam time: 7Be(p,γ)8B and 12C(α,γ)16O.

ACTIVITY from the PG-Camerino group: 1) GAMMA. Participation to the data acquisition and hardware developments (Das Gupta, Natali, Saltarelli, Tabassan) 2) ERNA. Three months of beam time for the 7Be(p,γ)8B (Madaffari, Trippella, Saltarelli)

ACTIVITY 2011 - Interpretation

Collaboration with the University of Victoria (Canada) and Observatory of Torino (INAF) for nucleosynthesis calculations incuding Be-Li (Palmerini to spend a total of 5-6 months in Canada)

Li vs heavy nuclei in open clusters of the galactic disk (Maiorca: new observationa runs w. VLT, TNG, plus new chemical evolution models for galaxies)

New proposal for Hershel observations in collaboration w. Leuven (Belgium), Keele (GB), Torino, Manchester (GB): aim is measuring isotopic ratios for light nuclei, including 6Li/7Li & CNO isotopes

ACTIVITY 2011 - Hardware

GAMMA: Acquisition system: double ADC with electronics (detectors to be provided by LNS). Mounting & tests in LNS.

ERNA: New Si detectors for the DE-E spectrometer to be associated to the recoil separator. Mounting & tests in Caserta

RICHIESTE 2011

Publications since the opening of the PG collaboration (2008-2010)

Total: 37 Papers (PG) + 9 (Camerino)

Refereed: 12 (Perugia) + 5 (Camerino) (+ …… 3 posters from STUDENTS in 2010)

Other: 2 Master theses (Guerro, Maiorca) 1 PHD thesis (Palmerini) 1 post-doc contract (Palmerini:”Fondazione CRP” + INFN: THANKS PASQUALE!

In 2011: 2 Master theses (Madaffari, Trippella) 1 PHD Thesis (Maiorca) post-doc in Victoria (Palmerini)