The FARCOS project
Collaboration: INFN (CT, LNS, MI, NA; Italy), GANIL (France), Un. Huelva (Spain)
Synergies: Fazia, Neutron detectors, Spectrometers, …
Physics case: dynamics and spectroscopy
1. Imaging in heavy-ion collisions
2. Spectroscopy of exotic nuclei:
– In heavy-ion collisions MPCS: Multi-Particle Correlation Spectroscopy
– Direct reactions
FARCOS: Femtoscope ARray for COrrelations and Spectroscopy
300 m
1500 m
Double-sided Silicon Strip
CsI(Tl) + D
32 x 32
32 x 32
6.4 x 6.4 cm2
4 cm
Angular resolution: ~0.2o at d=60 cm
Farcos as a modular correlator
Event characterization (4)
Correlations
Coupling to 4 detectors for dynamics studies (LNS, GANIL, NSCL-MSU, …)
Chimera @ INFN LNS
1m
1°
30°
TARGET
176°
Beam
1192 Si-CsI(Tl) Telescopes
SiCsI(Tl)
ΔE(Si)-E(CsI)
Charge Z for particles punching throught the Si detector
PSD in CsI(Tl)
Z and A for light charged particles
ΔE(Si)-ToF
Mass for particles stopping in the Si detector
E(Si)-Rise time
Charge Z for particle stopping in Si detectors (NEW)
ΔE(Si)-E(CsI)
Charge Z and A for light ions (Z<9) punching throught the Si detector
HI
pd
t
3He
LiBe
~300 μm
3-12 cm
Particle identification (as in Chimera)
V(t)t
slowfast
Farcos array features
• High angular resolution (<0.5o):
• Flexibility: allow coupling to
– 4 detectors, magnetic spectrometers, other correlators
– Neutron detectors for n-p correlations (future)
• Low thresholds for low energy experiments at Spiral2 and Spes
– pulse-shape on silicon and digitalization (future, interface to Fazia project)
Density dependence of the asymmetry term in nuclear EoS
E(, ) E , 0 Esym () 2 n p
n p
B.A. Li et al., Phys. Rep. 464, 113 (2008)???
Many approaches… large uncertaintiesMicroscopic many-body, phenomenological, variational
Symmetry Energy: who cares?
GDR & PYGMY RESONANCE
skins
halos
resonances
Supernovae, neutron stars
Lassa @ MSUImbalance ratios
FOPI @ GSIElliptic flow
Chimera @ LNSCompetitiion Inc. Fusion / DIC
• Isospin diffusion, fractionation, isoscaling phenomena…
Chimera@INFN, Indra@GANIL, Lassa@MSU, …
• n/p energy spectra and angular distributions
• p-p, n-n and n-p correlation functions
Producing density gradients
Large N/Z to enhance effects of Esym() 124Sn+124Sn (N/Z=1.48), 48Ca+48Ca (N/Z=1.4), 197Au+197Au (N/Z=1.49)
Radioactive beams…
Pre-equilibrium n,p Expansion Multifragmentation
Sec. decays!
Ebeam<100 MeV
n
p
Heavy-ion collisions: open issues
• Pre-equilibrium neutron/proton emissions: the most sensitive probes of Esym()
– n/p relative energy spectra– p-p, n-p, n-n two-particle correlation functions
• Space-time characterization: different particles emitted by several sources & over different time scales– Need space-time probes to disentangle sources
t as short as 10-22 sec
r as small as 1 fm“femtoscopy”
Correlation femtoscopy in HIC
d p
p
Femtoscope
p 1
p 2
1+R
(q) 1+
R(q)
q (MeV/c) q (MeV/c)
proton-proton deuteron-alpha
6Li
Sensitive to space-time properties
1p
1 R(q) k
Ycoin
p1,
p2
Yevt .mixing
p1,
p2
2p
q
rel
High angular resolution required!
ResonancesLow q (rel) measurements
Imaging correlations, “Femtoscopy”
Fast simultaneous emitting sources (pre-equilibium)
Source size
Slow sequential emissions (evap.)
14N+197Au E/A=75 MeV
G. Verde et al., PRC65, 069604 (2002)
q e
R(q) 4 dr r2 S(r)K (r,q)
Space-time images
Source function: Spatial distribution of proton emitting source in HIC: “femtoscopy” - measuring sizes r~1 fm and times t~10-21s
Farcos for complex particle correlations
r (fm)
S(r
)
Imagesd-
-6Lip-p
Different particles emitted by different sources and at different times (hierarchy)
Event characterization required ! ==> Coupling to 4 mandatory
p-p
1+R
(E* )
E*(MeV)
d-
6Li-
Multi-Particle Correlation Spectroscopy (MPCS)
Expansion
HIC and correlations as a spectroscopic tool
Several unbound species in just one single experiment!
10C*Not only EoS…
MPCS: 8B and 12C
Event mixingModified event mixing
3-alpha correlation function
12C states: sequential decay
C+Mg, E=53 MeV/u
F. G
renier et al., N
PA
2008Indra data
12C 12C Be
LASSA data
Spin of 8B states
W.T
an, PR
C 2004
J=1+
8B p+7Be
Accessing spins and branching ratios (sequential decay paths)
Multi- correlations: Hoyle and Boson condensate states
2 4 6 8 10 12 14
Ek (MeV)
1+R
(Ek)
2-2p correlations: states in 10C*
F. G
ren
ier, A
. Ch
bih
i, G. V
erd
e e
t al.,
Nu
cl. Ph
ys. A8
11
(20
08
) 23
3
p-p- four-particle correlations
10C 6Be+ (2p+)10C 8Be+p (+)p
10C 9B+p (+p)p
Disentangle sequential decay paths
10C
9B6Be
8Be
Symmetry energy and pp, nn and np correlations
Asy-stiff
Asy-soft
Symmetry potential
neutron-neutron
proton-proton
proton-neutron0.0
0.5
1.0
1.5
1
2
3
4
1
3
5
7
q (MeV/c)1+
R(q
)
52Ca+48Ca E/A=80 MeV
pp Sources
Asy-stiff: more localized source
Imaging
Future perspectives: pp, nn, np correlations! Coupling to neutron detectors
Neutron-proton correlation expts
neu
tro
n-p
roto
n
Ghetti et al, PRC 69 (2004) 031605Protons
Neutrons
Emission chronology sensitive to Asy-EOS
…difficult experiments
n/p experiments @ MSU
n detectorsLiquid scintillators
p detectorsDE-E (Lassa)
M. Famiano et al., PRL97, 052701 (2006)M.B. Tsang et al., PRL102, 122701 (2009)
112Sn+112Sn vs 124Sn+124Sn E/A=50 MeV
Esym () 0
n/p spectra ==> 0.7
Spectroscopy: “stand-alone” mode
Example:8He beam @ Spiral (GANIL) E/A=15.4 MeV8H + p 7He + d8H + p 6He + t
Shell structure close to drip lines
Similar experiments at LNS (FRIBS) or at LNL(SPES)
Spes: low energies (Pulse shape on 1st Silicon)
Must2 expts
Spectroscopy: “coupling” mode
FRIBS beams at the LNS of Catania
34Ar+p33Ar+dCorrelator (33Ar residue)
33Ar
34Ard
Chimera (d)
Correlator • Heavy core: Magnex at ~ 0o
• Scattered d with Correlator
• Spiral/Spiral2, Spes, …
Day-1 experiment at the INFN-LNS
Imaging correlations at low energies
• Perspectives at Spiral2 and Spes:
Imaging in fusion, fission, DIC, N/Z effects on limiting temperatures and reaction mechanisms, particle emission chronology
Requires low identification thresholds: pulse-shaping techniques on silicon detectors
• Chimera solution, Fazia implementation (digitalization of silicon signals)
• Future issue: Pulse-shape capabilities in integrated electronics (ASIC, etc.)
Workshop in 2011
• Catania, probably spring or early fall 2011– Integrated electronics for silicon detectors, new
solutions, pulse-shape in integrated solutions, coupling to different detectors (also neutrons, gammas, spectrometers, …), others
You are all very welcome: need to build up synergies
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