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