3 sujets IRFU/DEDIP

Dernière mise à jour : 19-04-2018


• Particle physics

 

Towards a high spatial resolution pixel detector for particle identification: new detectors contribution to physics

SL-DRF-18-0701

Research field : Particle physics
Location :

Service d'Electronique, des Détecteurs et d'Informatique (DEDIP)

DÉtecteurs: PHYsique et Simulation (DEPHYS)

Saclay

Contact :

Nicolas FOURCHES

Paul COLAS

Starting date : 01-09-2018

Contact :

Nicolas FOURCHES

CEA - DRF/IRFU/SEDI/DEPHYS

0169086164

Thesis supervisor :

Paul COLAS

CEA - DSM/IRFU/SPP/ILC

0169086155

More : https://doi.org/10.1109/TED.2017.2670681

Future experiments on linear colliders (e+e-) require improvements in the spatial resolution of pixel vertex detectors to the micron range, in order to determine precisely the primary and secondary vertices for particles with a high transverse momentum. This kind of detector is positionned closest to the interaction point.This will provide the opportunity to make precision lifetime measurements of short lived charged particles such as b-quarks (b-tagging) and taus. The search for extra-dimensions would benefit from such a detector.The technologies that are necessary to implement such detectors need to be further studied and within a limited amount of time should lead to a small prototype on which the main characteristics may be evaluated. Such technologies (TRAMOS, DOTPIX) are on the verge of giving a significant advance in vertexing and the efforts in this directions should be pursued. These technologies follow the trend of monolithic integration of the detector with the readout electronics. The fields of physics that these detectors open up should be reviewed and developed. These detectors open up the possibility for direct detection of short lived particles. These detectors should be implemented on the future e+e- collider,that have low hadronic background.

Development of an innovative muon tomography instrument for societal applications

SL-DRF-18-0288

Research field : Particle physics
Location :

Service d'Electronique, des Détecteurs et d'Informatique (DEDIP)

DÉtecteurs: PHYsique et Simulation (DEPHYS)

Saclay

Contact :

David Attié

Sébastien Procureur

Starting date : 01-10-2018

Contact :

David Attié

CEA - DRF/IRFU/SEDI/DEPHYS

(+33)(0)1 69 08 11 14

Thesis supervisor :

Sébastien Procureur

CEA - DRF/IRFU/SPhN/CLAS

(+33)(0)1 69 08 39 22

More : https://www.nature.com/articles/nature24647

Muon tomography, or muography, consists in using cosmic muons to perform deep imaging of structures. These highly energetic muons, produced in showers generating from the interaction of cosmic rays with the atmosphere, can indeed cross several hundred meters of stones before being absorbed. The outstanding progress achieved in the last years on particle detectors (spatial resolution, robustness, electronics, etc.) have recently elicited a high interest for muography in many different fields.



A first muon telescope prototype was built and tested in 2015, using Micro-Pattern Gaseous Detectors (Micromegas) with a patented multiplexing scheme. The next year, three new telescopes were deployed around the Khufu's pyramid in Egypt, showing their robustness in extreme conditions (temperature, dust, etc.). Their detection of the "ScanPyramids Big Void" in combination with Japanese instruments located inside the pyramid are a world premiere for outdoors instruments.



These developments triggered the interest of many industrials and researchers for this technology. But like an optical telescope, muon telescopes are quite directional and still not very compact. An elegant solution consists in using a Time Projection Chamber (TPC), which allows for a full trajectory reconstruction with better precision and in a quasi-isotropical way.



The goal of this PhD is then to design, build and test in real conditions such an instrument. One of the main key points concerns the TPC autonomy, in particular the gas consumption, but also its overall stability in outside conditions. A sealed or semi-sealed TPC with a gas purification system, easily transportable and resistant to environmental variations would be a major breakthrough in muon tomography and for gaseous detectors in general.



Through this project, the PhD student will have the opportunity to cover a large spectrum of activities (design, integration, detector characterization, electronics, data analysis, simulation, etc.) and will then acquire skills in multiple aspects of experimental physics. The small size of the team (~6 people) will also ensure a great visibility to his/her work.

Development of Picosec Micromegas for fast timing in high rate environments

SL-DRF-18-0579

Research field : Particle physics
Location :

Service d'Electronique, des Détecteurs et d'Informatique (DEDIP)

DÉtecteurs: PHYsique et Simulation (DEPHYS)

Saclay

Contact :

Thomas PAPAEVANGELOU

Esther FERRER RIBAS

Starting date : 01-03-2018

Contact :

Thomas PAPAEVANGELOU

CEA - DRF/IRFU/SEDI/DEPHYS

01 69 08 2648

Thesis supervisor :

Esther FERRER RIBAS

CEA - DRF/IRFU/SEDI/DEPHYS

0169083852

Personal web page : http://irfu.cea.fr/Pisp/esther.ferrer-ribas/

Laboratory link : http://irfu.cea.fr/Phocea/Vie_des_labos/Ast/ast_service.php?id_unit=5

Our R&D activity on fast timing with Micromegas detectors started as an RD51 Common Fund project in

2015. The performance achieved during the first tests (see attached publication) has resulted to a grown

interest on the field within the RD51 institutes but also beyond them. Already there are teams from Greece

(Athens, Thessaloniki) and China (Hefei University) that have joined the initial collaborating groups from CEA,

CERN and Princeton. New Micromegas prototypes have been built at CERN, to add improved characteristics

to the initial CEA prototype. Furthermore, teams from Portugal and Russia are starting R&D on carbon based

photocathodes (Diamond or DLC) and secondary emitters. We plan to address numerous topics in view of the

use of the proposed concept in experiments: lifetime (of the photocathodes in particular), robustness (spark

protection), scaling to multichannel readout, large area coverage, front end electronics, high rate and so on so

forth. R&D on solid converter (photocathodes, secondary emitter) will represent clearly one of the most

important subjects of this R&D and it will necessarily involve various expertize from different fields. The PhD

student will actively participate in many of those developments. He/She will:

a) work on the development of a multi-channel prototype (few tens of strips or pads).

One of the tasks proposed in this thesis is to build such a multichannel detector, (about 5x5cm2), and have it

tested for mid-2018 before the writing of the Technical Design Report by the ATLAS collaboration foreseen for

end 2018. The first step on this R&D will be to study the effect of the fragmentation of the anode and the

implied charge sharing on the performance of the detector. In the first stage the anode will be non-resistive in

order to directly compare with the existing data and isolate the effect of the fragmentation. The first prototype

will have pads arranged in a honeycomb geometry and its size will be limited to ~5 cm. The number of the

readout channels will be ~10. The fabrication is planned for June 2018, in collaboration with CERN. A

new chamber and PCB board with strips will be designed and built during the 2nd half of 2018 at SEDI. A

version with resistive strips is also planned, having active area of ~5x5 cm2.

b) participate in the development of diamond based photocathodes with sufficient photoelectron yield and

investigate diamond based secondary emitter as an alternative.

The development will be carried out at the CEA/DRT/List/DM2I/LCD laboratory, under the supervision of

Michal Pomorski. The Diamond Sensors Laboratory counts 20 researchers and holds ten years of expertise in

diamond materials: from thin diamond films synthesis to modifications of diamond nanoparticles. The team is

one of the largest and best known groups in France in diamond research.

We plan to develop: i) Boron-doped Nanocrystalline Thin Diamond Films (BNCD) as Photocathode. Ii)

Diamond Nanoparticles (ND) Decorated Surfaces as Photocathode. iii) Thick Diamond Films as Secondary

Emitter investigating also commercially available diamond films. The PhD student will have to get familiar with

the use of some of the facilities and will follow the sample production. His main task however will be the study

of the performance of the samples, as it is described in the item c) bellow.

c) establish a platform to measure the photocathode quantum efficiency (QE)and study the timing

performance of the prototype at the IRAMIS fs UV laser and at the RD51 test beam facilities at CERN.

The QE of a photocathode under study can be estimated relatively to a known photocathode using a cosmic

ray telescope and two identical detectors, operating under the same conditions. Absolute measurements can

be performed with the use of a UV spectrometer. The student will be responsible for the establishment of the

setup and will use it to characterize the photocathodes. Another setup using a powerful continuous UV lamp

will be needed to study the aging properties of the photocathode. The most performing photocathodes will be

used for the measurements with charged particle test beams at CERN and at the IRAMIS femtosecond UV

laser.





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