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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 2:00 |
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Conference: Bucharest University Faculty of Physics 2015 Meeting
Section: Optics, Spectroscopy, Plasma and Lasers
Title:
Scintillating fiber spectrometer for measuring energy electrons accelerated by the interaction between hyper intense laser beam and a jet of helium
Authors:
Tiberius GEORGESCU
Affiliation:
CETAL-INFLPR, Facultatea de Fizica,Universitatea Bucuresti
E-mail
tiberius.georgescu@yahoo.com
Keywords:
spectrometru, fibre scintilatoare, accelerare electroni, laser, plasma
Abstract:
Having been accelerated by the interaction between the laser and the Helium plasma, the beam of electrons is passed between the poles of a strong electromagnet where the electrons are deflected depending upon their energies: the most energetic will be least deflected and the least energetic will be subjected to the highest deflection.
The positions of the electrons exiting the electromagnet are determined by their interaction with an arrangement of scintillating, light transmitting fibers: when the electron hits the scintillating fiber, the latter emits a number of photons, depending on the energy of the impacting electron, which are guided through the fiber towards the photomultiplier. The fibers detecting the high energy electrons are placed in a plane perpendicular to the laser beam propagation direction and the fibers for detecting low energy electrons are placed in a horizontal plane.
Scintillating fibers can cover large detection areas, are flexible, can be coupled to a photomultiplier outside the vacuumed interaction chamber, without signicant loss of light.
The end of each fiber is connected to a corresponding channel on the photomultiplier. To align the 64 fibers to the 64 channels of the photomultiplier, I have designed the fibers’ mask, its support and the housing of the electronic board in such a way that it allows for adjustments in all three directions of space.
The photomultiplier’s gain is dependant upon the voltage with which it is supplied: from around 103 @500 V to 106 @1000V. Supplying this voltage is a dedicated unit, remotely controlled from a computer using the LabView environment.
The photomultiplier is placed on a circuit board also containing an Application Specific Integrated Circuit(ASIC) dedicated to processing and shaping the electronic pulses coming from the photomultiplier in a form suitable for binary conversion with minimal loss .The test board converts the photomultiplier’s output signal into digital data which can then be analyzed using the appropriate software.
All of the above electronics are controllable through the Labview software.
References:
[1] Electron Spectrometer for multi-GeV Laser-Plasma accelerator
N. Drenska , R. Faccini, C.Gatti, S. Martellotti, P.Valente
[2] Hamamatsu Photonics Photomultiplier tubes handbook:
https://www.hamamatsu.com/resources/pdf/etd/PMT_handbook_v3aE.pdf
Acknowledgement:
CETAL-INFPR
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