flerov laboratory of nuclear reactions keep calm and...
TRANSCRIPT
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!