Synthesis of plastic scintillator. Ildefonso León Monzón Universidad Autónoma de Sinaloa

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1 Synthesis of plastic scintillator Ildefonso León Monzón Universidad Autónoma de Sinaloa

3 MUON BUNDLE triggered by plastic scintillator modules from ACORDE

4 Plastic Scintillator how does it work? Excitation of base plastic by radiation Base plastic Foster energy transfer ( resonant dipole-dipole interaction) Emit UV ~340nm 10-4 m PPO (~1%) photon Absorb UV photon Emit blue ~400nm photon Detector (PMT... ) POPOP (~.03%)

5 Why to use P-Terphenyl and POPOP? Quantum efficiency from a typical PMT is around 420 nm

6 Once the method was under control, next step was to try bigger volumes.

7 Plastic made of Polystyrene dopped with PPO (1% w/w) and POPOP(.05% w/w).

9 Emission of the 0,5% PPO and 0,01% POPOP solution in the mixed solvent: Nemchenok et at. Emission, relative units Wanelength, nm

10 Up to now everything looks nice. How to construct the detector?

11 Counting cosmic rays...and coincidences!

12 Measuring quality Minimum Ionizing Particle: It will be carried out using cosmic muons. Light yield: Number of photons created by MIPS, and/or Radioactive sources Optical attenuation λ: exponential decay as a function of distance Time response: Measurement of fast and slow components (Luminescence and fluorescence) Aging, number of photons as a function of time.

13 CALIBRATION: charge per QDC channel To know the amount of charge entering by ADC channel, it is necessary to input a well know signal to each channel into the QDC. A H B V1718 QDC V965

14 Data fitted to a linear function

15 Once calibration is know, next step is to measure: 1 p.e

16 Example: PMT from OPERA

17 PMT GAIN The relation of 1p.e position as a function of voltage is called GAIN of the PMT (it is recommended to equalize all PMT's at same gain in an experiment) The position of 1p.e must be as far as possible from pedestal. Its position depends of PMT design.

19 Calibration almost finished (for one channel!) Next tasks... The calibration steps are clear. Now it is necessary to calibrate last 15 channels. Two (Bachelor) students will be enrolled. One Student from Chemistry Faculty will be working on the process of polimerization and developing a protocol for security reasons: Substances are TOXIC.

20 FUTURE: The experience in the synthesis of plastic scintillator, bring us the opportunity for innovation, it is possible because we have complete control about time polymerization, dopants concentration, etc. Now we will try to work in a plastic doped with metals, such as Gadolinium, Boron, and some other lanthanide metals.

21 Gadolinium: Why to use Gd? It has highest cross section for absorbing neutrons. Some experiments use a concentration of 0.1% by weight of Gd (Daya Bay). But, why could be that relevant for us? After a discussion with a colleague from Chemistry Faculty, we conclude that it is possible to obtain a COMPLEX compound with Gd. And... We could increase our concentration of Gd up to a value of 3 % or even more, 10 %.

22 Gadolinium complex are used in Medicine: NMR The plan is to start to work with not TOXIC Compounds and obtain a COMPLEX containing Gd. Of course, this must be dissolved in our polymer with a concentration as high as possible. Of course, we need to optimize concentration and attenuation length, as well as timing resolution after Gd is loaded.

23 Reaction for neutron detection The gadolinium-loaded scintillator are chosen for the anti-neutrino experiment because it offers two important advantages over pure hydrocarbon-based scintillator. Firstly, a large thermal neutron capture crosssection of the isotopes 155,157Gd (61,400 and 255,000 b) Shorten the neutron capture time. And a release of a high-energy (8 MeV) gamma cascade after thermal neutron capture on Gd results in a neutron capture signal well above the radioactivity backgrounds

24 Advantages of using plastic scintillators High Flash point (>90 C): Security reasons! If a high concentration is required, there is no phase separation or sedimentation. It is possible to reach concentrations up to 3%, or even more with good transparency Because it is solid, it is possible to have independent sectors in a detector. Good for mainteinance and reparation. A concentration of 3% could reduce a detector of 100 Tonne of LS, to 5.5 Tonne. If last is reached, there is a good opportunity for basic research with modest budget.

25 Other Applications 1) Nuclear Reactor monitoring 2) Applications for Dark Matter experiments (After change of dopant) 3) Civil Applications: Monitoring of radioactive material (terrorism) 4) Measurement of solar activity

26 Some applications of other dopants

27 Summary Synthesis method of polystyrene scintillators are under control We have a good response for detecting cosmic rays, mainly muons. There are good opportunities for innovation and look for other novel materials We have started a project research in UAS, for synthesis of materials for neutrino, antineutrino and neutron detectors Large area and volume detectors are now possible with modest budget. And much more...for next talk!

28 Thanks!

Neutrino Physics. Neutron Detector in the Aberdeen Tunnel Underground Laboratory. The Daya Bay Experiment. Significance of θ 13

Neutrino Physics. Neutron Detector in the Aberdeen Tunnel Underground Laboratory. The Daya Bay Experiment. Significance of θ 13 Neutrino Physics Neutron Detector in the Aberdeen Tunnel Underground Laboratory John K.C. Leung Department of Physics, HKU On behalf of CUHK, LBL & IHEP Presented to HKRPS on June 21, 2007 Neutrinos have