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Semiempirical MonteCarlo for FAZIA
Napoli, 3-5 October, 2007 Napoli, 3-5 October, 2007
Giovanni Casini INFN Florence
Silvia Piantelli and Giovanni Casini
Some Reactions of FAZIA interest
At Bologna (dec 2006) we decided to start with some systems to study physics and spurious effects
• NiNi at 10 and 40 AMeV
SnSn at 40 AMeV
NiSn at 10 AMeV
Kr+Ca at 5AMeV
Deep inelastic and Fusion Reactions
We started with NiNi at 10AMeV At the SPIRAL2 and SPES energies, dominant
mechanisms are Deep inelastic collisions (DIC) and Fusion reactions (FR): we cannot disregard them!
For the moment the DIC are better developed and most 'results' concern these ones, till now
We also started some FR simulations We think to also include some pre-equilibrium effect
(i.e. emission before separation in PLF-TLF for DIC and emission before evaporation or fission for FR
MCARLO tree Random Generation of l (hbar) from l0 and lmax where lmax=lgrazing: triangular distribution
Decision if the event is a DIC or a Fusion FUS event (on the basis of l )
If DIC: •Random extraction of TKE within the range Vcb to Ecm •Sorting of the mass A (and thus the charge Z) of the PLF and TLF (primary); •Sorting of the CM-angles of the PLF and TLF (primary);•A recipe for the Excitation energy sharing;•A recipe for the Angular momentum sharing;
MCarlo: DIC
DIFFUSION PLOTWilczynski plot
These primary correlations can/must be tuned for the various reactions. The literature gives some parametrisations
MCarlo: DIC
DIFFUSION PLOT
The excitation energy can be shared, in a given event, following
(old) experimental results. The general trend is: equal energy
sharing for large b; tendency to equal temperature at small b. In
this picture TQP=TQT
MCarlo: FR If l<lcrit we can produce (complete) fusion. We have to check the
amount of DIC vs. FR basing on the literature.
The Compound nucleus gets the whole excitation energy and
travels at 0deg in the LAB with the CM energy.
The CN can decay via evaporation or via fission (to be
implemented)
The evap vs. fission rate will be regulated basing on the
literature. The same for the mass asymmetry of Fission
Fragments.
DECAYThe PLF, TLF or the CN are excited.
The decay occurs via light particle and IMF evaporation with a parametrisation based on GEMINI as a function of the excited nucleus parameter set (A,Z,E*,l)
One can also select the fission channel; the parameters of this step (mass asymmetry, out-plane, in-plane) are suitably tuned
The kinematic quantities are written for all charged particles
Geometry (largely inspired from M.Gautier geometry)
trapezoidal detectors with active area r dθ=20mm and r sin θmed
dφ = 20 mm
1 sphere portion at r=1200mm for θ=0.5-22.5; Δθ=1.1, active 0.96 (1286 detectors, 20 rings)
1 sphere portion at r=1000mm for θ=22.5-43; Δθ=1.3, active 1.15 (2385 detectors, 16 rings)
1 sphere portion at r=700mm for θ=43-90; Δθ=1.8, active 1.64 (4631 detectors, 26 rings)
1 sphere portion at r=400mm for θ=90-170; Δθ=3.15, active 2.87 (1044 detectors, 26 rings)
TOTAL= 10346 detectors, 88 rings
The active region covers Ω/4π=81%
Geometry
θsinφ
θco
sφ
θsinφθc
osφ
In the simulation....
θsinφ
θco
sφ
Efficiency target thickness 0.238 μg/cm2
0.1μm of Si of entrance dead layer
first Si detector: 300 μm thick; second Si detector: 700 μm thick
Tof resolution: σdetector=(-0.3*Epart+3.3)ns; σbeam = 800ps
Energy straggling: σBohr=(0.1569*Z2*Zsi*thick(μg/cm2)/AsiMeV
Energy resolution: σelectronic=0.2MeV; σdetector=1.15 10-3 *Elost MeV
if a particle punches through the first Si, E=ΔE+Eres; the particle is identified in Z and A (if Z<15) from ΔE-Eres; if Z>15, A is given from E and ToF
if a particle is stopped in the first Si, if it punches through the first 30 μm of Si, it is identified in Z (from the pulse shape technique), A is given from E-ToF; if it does not punches through the first 30 μm of Si, A is given from E-ToF and Z=A/2
Hp: no PHD
true A=58 (58Ni+58Ni 10AMeV)
Neither the PLF nor the TLF punch through the first Si: A is given from E-Tof
TLF PLF
A from E-tof (stopped particles)
Punching-through particles
58Ni+58Ni 10AMeV DIC
primary 4π FAZIA detected (exp-equivalent)
58Ni+58Ni 10AMeV DIC
after evaporation 4π FAZIA detected (exp-equivalent)
58Ni+58Ni 10AMeV DIC (other parametrization)
primary 4π FAZIA detected (exp-equivalent)
58Ni+58Ni 10AMeV DIC (other parametrization)
after evaporation 4π FAZIA detected (exp-equivalent)
58Ni+58Ni 10AMeV DIC: PLF evaporation
warning 2: MC original charge for particles (not reconstructed) warning 1: MC original source of particles (not reconstructed)
58Ni+58Ni 10AMeV DIC: TLF evaporation
warning 2: MC original charge for particles (not reconstructed)
warning 1: MC original source of particles (not reconstructed)
58Ni+58Ni 10AMeV DIC particle multiplicities
geometry + efficiency
4π
1010
10
10
10
10
10
10c z>6 c z>6
58Ni+58Ni 10AMeV Fusion (first attempt)θ lab A E lab
after evap. + geometry +efficiency
primary