Key Experiments Key Experiments and Simulation: and Simulation: - - PowerPoint PPT Presentation

Key Experiments and Simulation: Status Report Key Experiments and Simulation: Status Report

E.Farnea

INFN Sezione di Padova, Italy

AGATA Week, Strasbourg, November 24th, 2005

Outline Outline

• Performance of the Demonstrator
• Some examples from “realistic”

Monte Carlo simulations

The AGATA Demonstrator The AGATA Demonstrator

5 asymmetric triple-clusters (in the simulation!) 36-fold segmented crystals 540 segments 555 digital-channels

Main issue is Doppler correction capability coupling to beam and recoil tracking devices However, the performance figures quoted in the following do include the effect of the tracking algorithms However, the performance figures quoted in the following do include the effect of the tracking algorithms

Performance Performance

Photopeak efficiency P/T Ratio ~14cm: Possible target-detector distance for the Demonstrator on PRISMA

1 MeV photons, point source at rest. Tracking is performed.

Effect of the recoil velocity Effect of the recoil velocity

Peak FWHM Photopeak efficiency Typical values for reaction products at PRISMA

1 MeV photons, Mγ = 1. Tracking is performed.

A simplified approach to PSA: Grid search A simplified approach to PSA: Grid search

• The analysis of the MARS in-beam experiment proved

that similar values for the peak FWHM are obtained using a (generic) genetic algorithm or a simplified grid search approach assuming a single interaction point per segment.

• How does the performance of the Demonstrator change

if such an approach is used?

Genetic algorithm

Raw F = 1 F = 2 F = 3

Grid search 16 keV R.Venturelli, Munich PSA meeting, September 2004

Possibility to start with a simplified PSA approach? Possibility to start with a simplified PSA approach?

Peak FWHM Photopeak efficiency

1 MeV photons. Tracking is performed. In the “pack” case,

• nly one interaction per segment is assumed.

Detector response

• 0.2

• 0.2

• rel. amplitude

• 1
• 0.75
• 0.5
• 0.25

• 1
• 0.75
• 0.5
• 0.25

• rel. amplitude

∗

• Pulse shape

generation Event generation Data Analysis

Electronics Response Function

Packing and smearing of simulated data γ-ray tracking Pulse Shape Analysis to decompose recorded waves

An example generator: cascadeEvents An example generator: cascadeEvents

• Written by F.Recchia
• Suited for fusion-evaporation reactions
• Cross sections and centre-of-mass spectra

read from CASCADE output files

• Discrete cascades generated with

GammaWare (O.Stezowski)

• Similar approach by C.Mihai (different

treatment of the continuum γ rays)

Short presentations by F.Recchia and C.Mihai Key Experiments and Simulation Team Meeting

AGATA vs. Conventional arrays AGATA vs. Conventional arrays

AGATA 1 AGATA 1π π GASP Conf. II GASP Conf. II

45 HPGe detectors (15 triple clusters) 40 HPGe detectors with anti Compton

Data generation and analysis Data generation and analysis

• Event production with cascadeEvents
• Response function of AGATA: list-mode file

with the interaction points produced via the Geant4 code

• Gamma-ray tracking with mgt and production
• f a reduced dataset in GASP reduced format

(photon energy and direction; information from the ancillary detectors)

• Analysis of the reduced dataset with the

standard GASP data analysis programs

“Realistic” Simulations “Realistic” Simulations

γ Fold 1 γ Fold 3 AGATA 1π array GASP Conf.II

28Si + 28Si@125 MeV. Particle detection

with EUCLIDES. Kinematical recalibration.

E.Farnea, F.Recchia E.Farnea, F.Recchia

Better quality of the spectra? Better quality of the spectra?

AGATA 1π array GASP Conf.II

28Si + 28Si@125 MeV.

Particle detection with EUCLIDES. No kinematical recalibration.

No difference

(save for efficiency)

if kinematical recalibration is NOT performed!!!

Another example: PRISMA + AGATA Demonstrator Another example: PRISMA + AGATA Demonstrator

• E. Fioretto

INFN - LNL

• E. Fioretto

INFN - LNL 195 MeV 195 MeV 36

36S +

S + 208

208Pb,

Pb, θ θlab

lab = 80

= 80o

• E (

E (a.u a.u.) .) ∆ ∆E ( E (a.u a.u.) .)

Z=16 Z=16 Z=28 Z=28

X Y X position X position Y position Y position

∆ ∆E/E < 2% E/E < 2% Z/ Z/∆ ∆Z ~ 60 for Z=20 Z ~ 60 for Z=20 ∆ ∆t t < 500 < 500 ps ps ∆ ∆X = 1 mm X = 1 mm ∆ ∆Y = 2 mm Y = 2 mm ∆ ∆t t ~ 350 ~ 350 ps ps, , ∆ ∆X = 1 mm X = 1 mm ∆ ∆Y = 1 mm Y = 1 mm

Simplifications are necessary to try and describe such a complex setup!

AGATA Demonstrator

MCP

Quadrupole Dipole MWPPAC Ion Chamber

Physics Input: PRISMA + CLARA Physics Input: PRISMA + CLARA

Mass Distribution Recoil Velocity

How can we emulate such physics input in a MC Simulation?

Data generation and analysis Data generation and analysis

• Goal of the simulation: evaluate the Doppler

correction capabilities of Demonstrator + PRISMA

• Major problem: reproduce the experimental

distribution of reaction products and velocities

• Solution: use experimental values! (N.Mărginean)

replaying an actual PRISMA+CLARA experiment

• PRISMA entrance detector emulated with a

pixel detector, pixel size corresponding to the typical position resolution

Data generation and analysis Data generation and analysis

• Since the peak FWHM is the only concern, only
• ne gamma per event is fired
• Mass resolution is neglected
• Trick to avoid contaminations from neighbouring

peaks in the final spectra: only one nucleus emits its “real” energy, the others get a different one (with a large energy difference)

• Velocity module of the recoil deduced from the

simulated time of flight

• Recoil direction deduced from the pixel

PRISMA+demonstrator PRISMA+demonstrator

78Ge: 2+→0+ energy

Other isotopes: 1332.5 keV

E.Farnea, N.Mărginean E.Farnea, N.Mărginean

FWHM 3.3 keV 2.6 keV 5.9 keV

Summary Summary

• The performance of the Demonstrator

Array have been reevaluated (see also http://agata.pd.infn.it)

• Work has been done on the generation

and analysis of “realistic” events

• Much work on that remains! Contributions

are more than welcome!