National funded projects
November, 2022 to February, 2023
ACCENT PRO 2000 S.R.L. (Dr. Mihai IOVEA)

Objectives of proposed experiment:

The scientific and experimental work proposed in this program will finally
allow us to predict and optimize various laser-driven gamma beam imaging
configurations, as a starting tool for further potential development of
stand-alone microfocus gamma ray sources prototype for being used in the
development of medical, scientific and industrial high-energy gamma
microfocus imaging applications.


    NP was running for three weeks, between 27 January and 10 February, and
    with two additional extension days granted, for 13 th and 14 th February.
  • Most of the first two weeks time have been spent for new main optical setup, probe beam and laser beam microscope
    mounting and aligning , for mechanical design of valve and target movement stages, magnet and microscope positioning
    stages, for parabola beam blocker stage, target alignment and for doing first preliminary experiments with Argon gas.
      Since no accelerated electrons
      were detected with Argon gas, in the last week we have decided to change the gas with
      He98%+N2% and the first results with the tantalum target came out, obtaining low quality gamma images due to the
      unstable operation of the gas valve.
    • Because the valve continued to create problems, main issue being shots without gas which created a partial damage of a
      laser mirror by returned scatter laser beam, we continue the experiments only with electrons, but a poor image with
      electrons was obtained in this case.
    • In the last day of the given three weeks time, have been analysed the valve problem and an algorithm for controlling it
      by watching the interaction chamber vacuum values was developed and the first experiments have revealed first very
      promising results.
    • In the last two additional days, for avoiding to make more damages, we decided to move the bremsstrahlung target to
      the Aluminium exit port Flange thinned at 2mm , and to put outside the chamber the electrons deflecting magnet ,
      setup being presented in Figure 1;
    • In the last
      day hours have been achieved the experimental gamma imaging data presented in following.

    Experiment Parameters

    Laser energy on target: 1,7
    2.04 J , Argon pressure: 2 bar, Gas valve predelay: 5 ms ; Valve open time: 10 ms , Laser beam valve height: 1.5 mm;
    Laser beam focal size (FWHM): 24 microns, Laser pulse duration: around 30 fs;


    IFIN HH/ ELI NP Team

    Ovidiu TESILEANU / CoPI
    Liviu NEAGU CoPI
    Yoshihide NAKAMIYA
    Georgiana GIUBEGA
    Florin NEGOITA
    Gabriel COJOCARU
    Andrei BERCEANU
    Catalin CHIOCHIU
    Laser Group members

    AccentPro2000 S.R.L. (AP2K)

    IOVEA / PI
    Marian NEAGU
    Edward Hermann
    Mihaela POTERASU
    Monica MIREA
    External collaborators
    Gabriel SULIMAN ( Politehnica Univ & ELI NP)
    Laura NITA (PhD student
    Politehnica Univ )


    • Definitely the three
      weeks granted beam time was totally insufficient for completing such complex experiments.
    • We have learned how to look for a stable point of
      gamma imaging experiment, where Laser shots are almost
      continuously good shots, based on the probe beam optimum acceleration channel image, interaction chamber
      vacuum variation on valve shots, EMP induced signal level and watching the Laser parameters.
    • The Argon gas is more suitable for the “gamma imaging applications” and low gas pressures data looks more stable.
    • The gas valve malfunctions created most of the experiments issues and should be further upgraded or replaced.
    • Despite the problems encountered, the
      final day hours gamma imaging experiments show promising results, an
      experiment continuation being necessary;
    • Main gamma imaging issues remained the
      gamma beam divergence and pointing variations that reached roughly up
      to 35 % of the field of view size, and a special further investigations for compensating these drawbacks are mandatory
      for the future of this set up imaging capability.
    • The Gamma emission during our experiments still was under optimum, being room for more experimental


    • We intend to continue our experiment by requesting a new beamtime for focusing on key mechanism of accelerating electrons by
      las er gas
      interactions for our specific needs: relatively low energy range useful electrons (up to 10 20 MeV) for producing useful gamma ray spectrum up to
      5 6 MeV. This requirement is due to the photon energies bigger than 5 6 MeV that are depositing negligible energy in thin standa rd scintillator
      (typically 0.3 1 mm) that is currently used for gamma high resolution imaging.
    • We will focus on finding the experiment parameters where are obtained stable shots imaging results, where Laser successive sh
      ots are almost
      similar in terms on intensities, beam size and centroid positions, even if in this case we are not reaching the maximum inten sit ies of electrons or
      photons .
    • We will further improve the
      use of the instruments for characterizing the interactions, by optimizing the probe beam visualization of the
      acceleration channel, computing the plasma electrons density with Phasics device, introducing a probe set up for an electro optical crystal for
      calculating the shot electrons bunch duration, improving the valve functionality and monitoring its behavior, monitoring the EMP induced signal
      level, watching the Laser parameters (power, near field intensity shape, spectrum) stability and corelating their values with th e quality of gamma
    • An improved mechanical design of gas valve and target moving stages will reduce many of the issues encountered;
    • Developing a gamma imaging set
      up and a dedicated software capable to analyze in real time each shot imaging by computing the image number
      of photons, field of view dimensions, average energy of incident gamma beam, pointing positions and showing continuously thei r v ariations from
      successive shots.
    • We
      intend to extend our applications investigation, from actual gamma imaging goals in in Since and industrial Non destructive Testing,
    • to
      acquiring gamma movies of objects in continuous movement/rotation by synchronizing the laser shots with the scanned object position
    • by analyzing the
      ultrashort gamma irradiation effect on bio samples, for studies regarding the effects of ultra short Gamma Ray shots in
      imaging techniques, where two specialized bio scientific groups will be partnering
Partners list: 
ACCENT PRO 2000 S.R.L. (Dr. Mihai IOVEA) (Romania)
ELI-NP (Romania)
Institutul National de Cercetare-Dezvoltare pentru Fizica si Inginerie Nucleara Horia Hulubei (Romania)
Setup used in Laser-driven gamma imaging experiments
Rabbit amulet Sample twenty-successive-shots averaged and aligned gamma image
Multiple-holes Sample ten-successive-shots averaged  gamma image