Keep calm and focus on ACCULINNA

Supervisor: Grzegorz Kaminski Students: Alexi Florica Nicoleta Martin Ansorge Janina Krzysiak Ana Chiriacescu

FLEROV LABORATORY of NUCLEAR

REACTIONS

Goals

1. ACCULINNA separator 2. Detectors: Si, scintillators (CsI), stilbene crystals 3. Performing calibration of detectors 4. Performing simulation LISE++ program

5. OTPC (Optical Time Projection Chamber)

ACCULINNA SEPARATOR

• Acculinna is a local separator which provides high quality primary beams or radioactive beams at E~25 MeV/n for physical experiments by fragmentation in flight method.

• Structure of light neutron-rich systems close and beyond the drip-line is the main goal of our investigations.

• We study nuclear reactions under a condition of complete kinematics.Therefore neutron detection is instrumental.

8He&10He: 3H(6He,p)8He & 3H(8He,p)10He reactions

ACCULINNA-2

Time of flight (ns) Time of flight (ns)

Δ

E (

MeV

)

Δ

E (

MeV

)

Δ

E1

(M

eV)

Δ

E1

(M

eV)

ΔE2 (MeV) ΔE2 (MeV)

Detectors of non-charged particles

(a)Stilbene scintilator of 80 mm in diameter and 50

mm thick encapsulated into an aluminium housing

(b)A scheme to a detection module

(c)Stilbene crystals and PMT’s (d)A layout of the neutron detection array in the measurement room

Detectors with crystals of Si and CsI

CsI crystals detectors

Si crystals detectors

CsI crystals detectors

CsI crystals detectors

Si crystals detectors

CsI crystals detectors

Si crystals detectors

Energy Calibration

The scintillation amplitude spectra for the stilbene crystal irradiated by γ-rays from 60Co and 137Cs.

The Compton scattering is the dominant interaction of γ-rays with matter, so we used Compton electrons to perform the energy calibration. The Compton edge is determined by using the formula :

Nc = Np + 1,177σ

PSD-Pulse Shape Discrimination

Fig.1 Typical neutron and γ-ray pulses for stilbene scintillator.

(a) An example of neutron– discrimination plot obtained with a stilbene scintillator;

(b) Data fit is performed by a default ROOT build in procedure using a Gaussian function.

(a) (b)

Fig.2 Division of pulse to slow and fast parts.

Dependence of PSD for different borders of fast and slow parts of pulse.

OTPC – Optical Time Projection Chamber

Study of exotic nuclei

Novel approach to kinematical reconstruction of

decay events (delayed-beta decays)

Allows for precise measurement of energy and

angular correlations of decay products

First direct observation of 2p decay (Fe-45)

Downsides: Long dead time

Low energy res (~20%)

OTPC – Optical Time Projection Chamber

TPC with optical readout

Proportional gaseous

ionization detector

Allows for 3D reconstruction of tracks

Gas mixture optimization:

heavy ions vs low-energy

protons

Principle of Operation

CCD image

Photomultiplier

signal

Δt

Set-Up Using Alpha Particles

3650V 3700V

3850V 3800V

3750V

scattering on nucleus

2p Decay Events of Ni-48

Identification using

standard TOF-ΔE method

CCD

48Ni

44Cr decay time

Implantation

Decay

Decay time: 42.8 ms Exposition time: 33 ms

46Fe decay time

Decay time: 14 ms Exposition time: 33 ms

Detector mounting

Measurement area

Internal parts of the detector

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α α 10 cm

Drift velocity calculation

Thank you for your attention!