Hadron Calorimeter for HERA-H1
Design and Construction of a Hadron Calorimeter for Use in the H1 Experiment Carried out at the HERA Electron-Proton Collider
Tech Area / Field
- INS-MEA/Measuring Instruments/Instrumentation
3 Approved without Funding
Joint Institute of Nuclear Research, Russia, Moscow reg., Dubna
- Federal State Unitary Enterprise Research and Development Institute of Power Engineering named after N.A.Dollezhal, Russia, Moscow\nNIIEPr (Electronic Devices), Russia, Moscow
- DESY, Germany, Hamburg
Project summaryThe Project is a part of the experimental research carried out at the HERA Electron-Proton Collider at the DESY Center for High Energy Physics by the H1 scientific collabo-ration. This collaboration involves groups of physicists from 12 countries. The research is devoted to the fundamental scientific problems.
HERA is a unique collider where 820 GeV proton beam is collided with 30 GeV electron beam. So, as soon as this collider was put in operation, it became possible to study interactions of point-like (having no structure)- electron with proton - more complex particle consisting of quarks and gluons. A new kinematic region of deep inelastic lepton scattering becomes accessible for investigation at the HERA experiments. This unique kinematic region makes it possible to observe the final hadronic fragments and study the weak neutral and charged quark currents at high momentum transfer.
The H1 detector has been operating successfully since 1992. Now an upgrade of H1 detector is planned. This upgrade includes the construction of a new hadron calorimeter to measure the jet energy flow along the proton beam, and to minimise the losses of total transverse momentum measurement due to hadron emission in the direction close to the beam pipe. Measuring of energy, emitted into a narrow cone around the beam pipe, allows one to identify the diffractive events among those of deep-inelastic processes as well as exclude the background arising because of beam-gas and beam-wall interactions. This calorimeter is called PLUG in accordance with it purpose.
Thus, in the contexts of the H1 upgrade, the project means the construction of the hadron PLUG-calorimeter arranged inside a cylindrical hole in the return yoke of the H1 solenoid magnet. As the calorimeter must be placed close to the proton and electron beams, it should be operated in rather hard conditions caused by radiation background as well as high magnetic field.
A sampling version of the PLUG-calorimeter has been chosen for realization in the H1 experiment. It comprises the following main elements: copper plates - as absorber layers; radiation hard plastic scintillates - as active sensitive layers; photo-multiplier tubes (PMT) insensitive to magnetic field - as photo-receivers of scintillation signals. Thus, the following problems should be solved in the framework of the Project:
- Design and production of PMTs insensitive to magnetic field up to 1 Tesla. The PMT time resolution must be better than 1 ns. To achieve the required energy resolution the PMT response must be linear within the dynamic range of light signals produced in scintillation layers of the PLUG-calorimeter.
- Production of radiation hard plastic scintillates which provide a stable response up to radiation doses of 10 kGy.
- Design of the PLUG-calorimeter based on Monte-Carlo simulation of its response and detailed construction of its elements to ensure the required characteristics and reliable of its operation under the H1 experimental conditions.
The project realization requires considerable efforts to make an optimal design of the calorimeter in the Research and Development Institute of Power Engineering (ENTEK) and to organize production of radiation hard plastic scintillates in the Joint Institute for Nuclear Research (JINR) and to develop and produce PMTs insensitive to magnetic field, in the Scientific Research Institute for Electronic Devices (SRIED). Project execution will allow one to transfer technologies commonly used earlier in the production of weapon of mass destruction, to development and production of special photoelectric devices used in base scientific researches.
Technical approaches to solve problems at different stages of the project are based on modern developments of design and production of PMTs insensitive to magnetic field, and radiation hard plastic scintillates.
It is planned to apply silicon fine mesh dynodes in the PMT production. That is a unique approach, which provides a better stability of PMT response in magnetic field, than ones caused by PMT with metallic fine mesh dynodes.
It is planned to apply the methods of injection molding; polymerization in blocks and extrusion using radiation hard dopiness In the process of production of radiation hard plastic scintillates.
The working environment in high energy physics research facilities such as applied in DESY, is usually tensioned by the fierce competitive nature of frontier international research, balanced by the need to select cost-effective solutions while maintaining acceptable performance standards. Aspects of this special environment have much in common with the market-oriented operating conditions. Thus, experience gained from this project should assist in the transition of the involved Russian enterprises to a market economy. The outcome of the collaboration has several benefits:
- First, the hadron calorimeter will contribute considerably to an important international experiment, and will provide an excellent "shop-window" for the commercial capability of Russian military industry enterprises involved in the project.
- Second, the participation of Russian industry will allow the physicists and engineers of JINR Dubna, to participate equally and fully in the experimental program at DESY.
- Third, scientists and engineers from the Russian military industry enterprises will have gained expertise in the technology and construction disciplines current in the advanced market economies through the close co-operation with DESY and its collaborating institutions.
- Fourth, it may well lead to the commercial exploitation of new developed technologies for non-military products.
A successful collaboration on this project could pave the way for more lucrative collaborative projects connected to the construction and exploitation of the next large project at CERN - the Large Hadron Collider or LHC, STAR experiment at BNL etc.
The role of foreign collaborators:
Within the framework of the project DESY is responsible for organization of the calorimeter installation into the H1 set-up and for general management of the experiment. The DESY contributions to the project are the following:
- copper absorber plates;
- part of readout electronics and data acquisition system, which is common for the H1 calorimeters;
- base program support of the H1 data analysis system.