Transcript Esperimento NUCL-EX Bologna (5 Ric) - INFN

Esperimento NUCL-EX
Rappresentanti Nazionali: M. Bruno (BO) G. Casini (FI)
Bologna (5 Ric), Firenze (9 Ric), LNL (6 Ric), Napoli (9 Ric),
Padova (1 Ric)
30 Ricercatori (25 FTE)
Collaborazioni: Ganil, Jyvaskyla, Dubna, Nevsehir Univ. Turkey
(BARC,TAMU, Moskow State Univ., Ohio State Univ.)
• Dinamica e Termodinamica Nucleare
• Formazione e Decadimento di sistemi nucleari (Fusione – Fissione,
Pre-equilibrio, Clustering)
• Fisica dell’Isospin verso SPES (Densità dei Livelli, Energia di Simmetria)
• FAZIA project
Apparati
Sperimentali
@LNL
FAZIA Dem.
GARFIELD
8pLP
RIPEN
Evidence of Strong deformation in alpha-like nuclei
24Mg+24Mg
@92 MeV, (8pLP + PPAC modules)
a detected in 8pLP, Residue detected in PPACs
E
a-Residue
angular correlation
F
G
BALL detector number
a-Residues Angular correlation is better reproduced by assuming an
Highly Deformed nucleus indicating a possible a-clustering stucture
A. Di Nitto et al., EPJ Web of Conferences 21, 02002 (2012)
CNR*11 Int. Conf., September 19-23, 2011 Prague, Czech Republic
GARFIELD + RING Counter: Central collisions: we expect that close to the
multifragmentation threshold, the produced fragments will be relatively cold. The
experimental reconstruction through correlation techniques of secondary decays in
such moderately excited fragments will allow us to trace back the primary
fragmentation pattern minimizing the model dependence of the procedure.
32S+40Ca
17.7MeV/A
32S+48Ca
17.7MeV/A
Level densities at low excitation energy are known to exhibit important
isotopic and odd-even effects, resulting in staggering effects in different
isotopic observables.
Analysis in progress
Sorting the events:
• Peripheral collisions:
many sources,
• Central collision one
source
Activities 2012-2013
2012/2013:
Two experiments approved by the LNL PAC:
1. Study of a-clustering using pre-equilibrium emission (V.L. Kravchuk)
2. Probing the Statistical decay in N=Z light nuclei (G. Baiocco)
One approved experiment at TAMU:
1. Study of nuclear level density at moderate excitation energy (A. Voinov)
Ideas for proposals at TANDEM-ALPI:
Jacobi and Poincare shapes of
Ba isotopes vs. mass asymmetry
of fission fragments
A. Maj, Cracow
Role of the entrance channel in the
production of complex fragments in
fusion-fission and quasifission
reactions in the framework of the
dinuclear system model
G. Adamian, Dubna
Study of fusion-fission dynamics
through fission fragment angular,
Mass distributions and neutron
multiplicity measurements
S. Appannababu, LNL and Delhi
RIPEN @ CN Van de Graaf accelerator
24 BC501 cylindrical
Liquid Scintillators
2 V1720 digitizer from CAEN (12 bit, 250 MS/s)
in the 8 channels VME version communicating with
a standard PC via a VME bridge (CAEN V1718).
• Energy release of impinging particle
• Time of flight and Palse Shape Discrimination
between neutron and g
8B
production in the reaction 6Li(3He,n)8B via
neutron angular distribution measurement
C. Rubbia et al., NIM A 568 (2006) 475
C.R. McClenahan et al., PRC 11 (1975) 370
R.E. Marrs et al.,PRC 8 (1973) 427
P. Van Der Merwe et al., NPA 103 (1967) 474
8B
g.s.
12C(3He,
Counts
 Previous experiments using two
different experimental techniques
(Positron Counting technique and
Neutron Time of Flight) give
very different results for the 8B
production cross section varying
by a factor of 3
n)14O
8B*
6Li(3He,np)7Be
g
TOF (ns)
RIPEN @ CN Van de Graaf accelerator
V.L. Kravchuk et al., To be published in
Phys Rev. Special Topic – Accelerators and Beams
ds/dW (mb/Sr)
12
6 MeV 3He+6Li  8B + n
10
g.s.
8
6
4
1st exc.
2
Total cross section
Reference
(68 ± 7) mb (g.s.)
(35 ± 7) mb (1st exc.)
Experimental result
65 mb (g.s.)
E3He=5.6 MeV
(neutron TOF)
75 mb (g.s.)
DWUCK4 calculation
(20 ± 3) mb
Positron counting
0
0
50
100
150
Neutron emission angle in CM (deg)
Test experiment scheduled from
July 26 to August 3, 2012 in view
of an experimental campaign at the
CN
Definition of Physics Cases for coupling
the neutron detectors with LCP
detectors (modules from 8PLP) and/or
gamma detectors (GALILEO)
FAZIA: Phase II
The 192 telescopes of FAZIA demonstrator will be ready at the
end of 2013.
Initially they will be coupled with : INDRA
Then with: GARFIELD@LNL, RIPEN@LNL and CHIMERA@LNS
Coupling FAZIA + INDRA
WITH STABLE BEAMS &
1st DAY EXP with SPIRAL2
Basic BLOCK: 4x4 telescopes
Transport properties of isospin asymmetric nuclear matter: neck emission and isospin drift
40,48Ca+40,48Ca
58Ni+58Ni at 30-45AMeV
at 15, 25, 35AMeV,
Related to deep-inelastic processes, isospin equilibration and drift;
isoscaling for massive ejectiles
78,86Kr+40,48Ca
---> 20-60AMeV
Related to the surface or volume expansion in central collisions
Richieste finanziarie per 2013
• Missione Interne
1 KE Riunioni collaborazione + 1 KE s.j turni LNS
• Missioni Estere
2 KE riunioni analisi Texas, riunioni Fazia, Assemblaggio
dimostratore Ganil
• Consumo
1 KE lavorazioni meccaniche, materiale test laboratorio
• Inventario
1 KE PC per analisi
SPARES
GARFIELD
Fragments and Light Particles
identification
• 2 Drift chambers : 180 micro-strip
detectors + 180 CsI(Tl) ( = 300 – 1500)
• Ring Counter: annular telescope,
Ionization Chamber + Si + CsI(Tl)
( = 60 – 180)
• Time of Flight system: 4 Position
Sensitive Parallel Plate Avalanche
Counters
Drift Chamber
14.5 MeV/A 32S+64Ni
THE 8pLP SPECTROMETER
11
The Experimental set-up: The TOF Apparatus
6 MeV 3He+6Li  8B + n
40 pnA, pulsed beam 333 ns rep. rate with 2 ns resolution
DE (15 mm) – E (200 mm) Silicon
Telescope
pickup
beam
1
2
3
4
8
3He
5
2 m Flight path
DW ≈ 3 mSr
D ≈ ±2o
6
7
1H
8 BC501 detectors covering angles from 15o to 140o in LAB
(500 mg/cm2) on Au (500 mg/cm2)
Background measurements:
1)7LiF (500 mg/cm2) on Au (500 mg/cm2)
2)12C (70 mg/cm2) & 3) without target
6LiF
Rutherford scattering of the beam on the Au
backing is used as normalization to
determine the 8B production absolute cross
section