GIF++ A New Gamma Irradiation Facility

Transcription

1 EDMS No. Rev Validity REFERENCE GIF++ Project CERN CH-1211 Geneve 23, Switzerland Date: 26/04/13 REQUIREMENTS GIF++ A New Gamma Irradiation Facility Abstract GIF++ (Gamma Irradiation Facility) in the North Area will replace the existing GIF of the West Area. GIF++ will meet the demand for higher photon radiation fields and will restore the possibility of a simultaneous, secondary muon beam. This document summarizes the requirements and specifications from the users. The document does not specify the responsibilities for procurement, installation and operation. Prepared by : D. Pfeiffer EN/MEF R. Guida PH/DT Checked by : A. Fabich EN/MEF F. Ravotti PH/DT Approved by : M. Capeans PH/DT I. Efthymiopoulos - EN/MEF Approval list: M. Capeans, I. Efthymiopoulos, A. Fabich, R. Fortin, R. Guida, D. Pfeiffer, F. Ravotti

2 Page 2 of 14 HISTORY OF CHANGES REV. NO. DATE PAGES DESCRIPTION OF CHANGES First draft for discussions Split of document into requirements and functional specs Including comments by R. Guida on gas zone Corrected version All Sent for approval All Version 0.5 with comments included

3 Page 3 of 14 TABLE OF CONTENTS GIF A NEW GAMMA IRRADIATION FACILITY INTRODUCTION THE SCIENTIFIC CASE FOR GIF FACILITY OVERVIEW BUNKER SOURCE-BEAM ARRANGEMENT AND IRRADIATION SPACE LARGE, PERMANENT USERS EQUIPMENT GENERAL INFRASTRUCTURE PREPARATION ZONE GAS MIXING ZONE COUNTING ROOM CONTROLS AND LOGGING SYSTEM USERS EQUIPMENT FOR TESTING IRRADIATOR IRRADIATOR LAYOUT IRRADIATOR INSTALLATION REFERENCES... 12

4 Page 4 of INTRODUCTION 1.1 THE SCIENTIFIC CASE FOR GIF++ The current LHC configuration is set up to produce proton proton collisions at a centre-of-mass energy of 14 TeV and a luminosity of several cm 2 s 1. The high luminosity LHC (HL-LHC) project however aims for a tenfold increase in luminosity for 14 TeV proton proton collisions [1]. Thus at the HL-LHC, the experiments will have to sustain rates 10 times higher than at the LHC. For the muon detectors, studies on particle generation and absorption predict that over most of the acceptance, the rate will be dominated by background due to neutral particles, photons and neutrons with energies below 1 MeV. In the most forward regions the contribution of penetrating particles will be significant, and the rates in the inner forward stations will reach the level of several khz/cm 2. Therefore the detailed knowledge of the performance of detectors under high particle fluxes and a precise understanding of possible aging of detector materials under permanent particle bombardment are crucial for an optimized design and efficient operation mode. New operating conditions or better-suited detection technologies must be studied. This demands a new series of studies on detector performance and stability, which cannot be carried out at the old GIF facility. The old GIF facility was created in the SPS West Area in the mid 90ies [2]. It combined irradiation by a high-rate 137 Cs source, providing a large area flux of photons with a typical energy of 662 kev, together with the availability of high energy SPS secondary charged particle beams. The GIF facility has been used extensively for many years, with scheduled source irradiations during some 50 weeks per year. Despite the disappearance of the West Area beam lines in 2004, the GIF facility is still heavily used to date. However, there is a need for a stronger source and for regaining the possibility to carry out simultaneous detector performance tests with a highenergy beam. To provide continuity with the present GIF, the new gamma-irradiation facility (named GIF++) will contain a 16 TBq Cs-137 source and shall be installed on a SPS secondary beam line. GIF++ will be used for two main fields of research: The first field deals with the radiation hardness of materials, small prototype detectors, electronic components and radiation monitors or dosimetry under a strong photon flux. The second field on the other hand is concerned by long-term behaviour of large particle detectors and requires additionally the availability of a high energy muon beam [3].

5 Page 5 of FACILTY OVERVIEW The GIF++ facility shall contain four main areas as listed in Table 1. The bunker provides the irradiation area hosting the photon source and receiving a secondary muon beam. Adjacent to the bunker should be an area for the mechanical preparation of the users equipment (preparation zone), a dedicated gas rack zone and two control rooms. The surface sizes are indicative and give an overview concluded from the requirements later in this document. Part surface Bunker Irradiation area 100 m 2 Preparation area Gas zone Counting room Area for detector preparation directly accessible from control room and adjacent to the bunker Hosts large part of the peripheral infrastructure and services (gas supplies and systems) Two separate control rooms for services and users with closest access to the preparation area and the bunker. Table 1: The four zones of the GIF++ facility 80 m m 2 Each 15 m 2 The bunker shall host the source at a location where the two opposite irradiation fields intercept with the nominal secondary beam line. The overall layout shall allow six teams to use the GIF++ facility in parallel (within the space constraints given below). I.e. gas panels should be provided accordingly. The facility shall be designed such that it can be operated in an unattended mode. 3. BUNKER The bunker is the actual irradiation area, hosting the source, receiving the secondary beam and providing sufficient space for users installations (detectors etc.). A possibility for installation of large permanent users equipment shall be forseeen for the following elements: two vertical cosmic muon trackers, one in the floor and one under the ceiling, two muon trackers, each one inside the bunker at the entrance and the exit of the secondary beam. 3.1 SOURCE-BEAM ARRANGEMENT AND IRRADIATOR SPACE Secondary beam Source-beam arrangement SPS secondary beam types (typical beam parameters). Primarily a muon beam (about 100 GeV/c, 10 4 muons per spill) is requested. The beam control/steering and logging should be provided in the common way. The photon source shall be placed adjacent to the secondary beam line without intercepting it. Its two irradiation fields overlap partially with the axis of the secondary beam line. Additionally, the source shall be manually displaceable perpendicular to the secondary beam. In one position it is as close to the secondary beam as possible, in the other position the axis of the source is

6 Page 6 of 14 aligned with the centre of the lower muon tracker. Source height The source shall be placed at secondary beam level Main area irradiation A free area for users installations stretching over 6 m from the source along the secondary beam line, laterally covering an angle of ±37 degree. Additional irradiation area Room height A free area for users installations stretching in the opposite direction of the main irradiation area over 6 m from the source along the secondary beam line, laterally free width of 1.3 m (across the beam line) and 2.7 m (side without beam line). 4.8 m or more above the floor in the irradiation areas and on transport paths (e.g. personnel entrance chicanes can be lowered to 2.5 m). Beam time - Irradiator: 24/7 throughout the year - Secondary beam: o o o Main user mode: few periods per year with each about two weeks Parasitic mode with muons: as much as possible (based on experience from previous years, one can expect parasitic muon beams for about 30-50% of the beam time, equivalent to about 2-4 months/year). Few periods per year of approximately two weeks duration in which a beam pipe is installed within the facility and electron beam is taken by CMS ECAL downstream from GIF++ Table 2: Source-Beam arrangement 3.2 LARGE, PERMANENT USERS EQUIPMENT The irradiator (photon source) is described in detail in section 8. Table 3 and Table 4 list the permanently installed particle detectors. Lower vertical cosmic muon tracker Upper vertical cosmic muon tracker Fine tracking chamber Centred 1.5 m off the secondary beam axis on the side of the irradiator. Starting 1.5 m away from the source in the main irradiation area. Width 2.4 m, length 2.8 m, installation height 15 cm. Requires electrical cabling and gas supply/return (flammable). Size about 1 m by 50 cm. Height about 50 cm. The upper muon tracker shall be mounted to the ceiling inside the perimeter of the lower muon tracker, but outside the direct photon field. Requires electrical cabling and gas supply/return (flammable). Size about 1 m by 50 cm. Height about 25 cm. The fine tracking chamber shall be a movable device. But usually it will be positioned on the floor directly between the irradiator and the lower vertical muon tracker Shielding of The lower muon chamber shall be shielded from the photon flux in

7 Page 7 of 14 the cosmic tracker lower muon Shielding of the upper muon chamber such a way that the flux stays below 1.5x10 3 Hz/cm 2. The shielding should leave a free height of 25 cm from the ground for the installation of the muon tracker. Shielding shall be placed reducing the hits from scattered photons so that the flux stays below 10 5 Hz/cm 2. This shielding should not cover the direct view towards the lower muon tracker. Table 3: Cosmic muon trigger setup Beam muon trackers Shielding of beam trackers Each a muon tracker (about 60 cm wide, 40 cm high, 20 cm thick including shielding) at the entrance and the exit of the secondary beam line inside the bunker. Requires electrical cabling and gas supply/return. Shielding shall be placed to reduce the flux from direct and scattered photons to less than 10 4 Hz/cm 2. Tungsten-rubber mats of 1 cm are requested for this purpose. Table 4: Muon beam trigger setup 3.3 GENERAL INFRASTRUCTURE False floor Reducing the secondary beam height above floor to 1.64 m. Suitable for supporting users equipment. Offering space for the lower cosmic muon chamber with its shielding. False floor shall cover at least the large irradiation zone in the bunker (together with the outer preparation zone). Environmental conditions Illumination Experimental gases Exhaust Temperature C, humidity 30-50%. After an opening of the bunker for large transports, nominal conditions should be reached within a period of 12 hours. Similar to a typical workshop area (about 400 Lux at 1 m above floor, neglecting temporary users installations). 6 distribution panels: 4 distributed around the main irradiation area, 2 next to the additional irradiation area; each panel provides four gas supply/return lines fed from the gas zone. Two exhaust pipes are required. Electricity 6 panels (distributed as above) each with 1 x 400 V (3PNE) and 4 x 230 V (Swiss or Euro plug?); 50 kw total electrical power together with preparation zone and control rooms. No dedicated UPS power is required. Ethernet Adjacent electronic racks Signal panels Cable routing patch 6 double Ethernet outlets (distributed as above) Installation space 3 x 3 electronic racks (19, 2 m high) in low radiation areas inside or just outside the bunker shielding. Maximum cable length 15 m from the closest irradiation area. 6 patch panels (distributed as above) shall provide permanent link to the counting room (cable types: lemo, coax, HV) Cable trays separated for DC, signal and AC for permanent and

8 Page 8 of 14 temporary cable installation. Mainly in the false floor with easy installation access. Additional cable trays along the inner side of the shielding walls are optional. Chicanes in the shielding shall allow cable routing from the control room/racks to the bunker. Compressed air Cooling water Personnel access 6 outlets (distributed as above), one for the irradiator from the EHN1 infrastructure (typical pressure as at EHN1/CERN). 6 outlets (distributed as above), demineralised, from EHN1 infrastructure, few L/min, 6 bar/3 bar. Allowing access with a minimum time delay to re-start the irradiation after an access. Allowing access with minimum restrictions in the event of a main user other than GIF++. One shall be able to bring small material (size of a desktop computer) to/from the bunker without causing larger time delays for reinitialization of the irradiation in the zone. Table 5: General infrastructure of the bunker 4. PREPARATION ZONE The preparation zone shall be located next to the bunker. It offers space to the users to set up their equipment before irradiation. Space for users equipment Storage of tools and small equipment False floor Environmental conditions Illumination Experimental gases Dedicated area of at least 4 m by 10 m. Fenced area, no roof required. Installation of office cabinets. Same requirements as in bunker. Equal height required for transport using a trolley from/to the bunker. none As in EHN1 4 distribution panels; each panel provides 4 gas supply/return lines fed from the gas mixing zone (more details are given in section 5). Electricity 4 panels (distributed as above) each with 1 x 400 V (3PNE) and 4 x 230 V (Swiss or Euro plug?); 50 kw total electrical power together with preparation zone and control rooms. No dedicated UPS power is required. Ethernet Signal panels patch 4 double Ethernet outlets (distributed as above) 4 patch panels (distributed as above) shall provide permanent link to the counting room (cable types: lemo, coax, HV) Cable routing Cable trays separated for DC, signal and AC for permanent and temporary cable installation. Mainly in the false floor with easy

9 Page 9 of 14 installation access. Compressed air Cooling water Access 4 outlets (distributed as above) (typical pressure as at EHN1/CERN). 4 outlets (distributed as above), demineralised, from EHN1 infrastructure, few L/min, 6 bar/3 bar Free access for personnel. Material transport for specified users equipment. Table 6: Layout and infrastructure of the preparation zone 5. GAS MIXING ZONE The gas mixing zone shall be located adjacent to the preparation zone and the bunker providing both with experimental gas (and mixtures). The gas mixing zone shall be provided with neutral and hazardous gas (mixtures) as listed below. As not all gases (mixtures) to be used are known at present, for each group additional gas supply lines shall be foreseen. The supply lines for gases with low vapour pressure shall be heated in order to ensure enough pressure at the arrival to the gas mixing zone. A schematic sketch of the gas distribution is shown in Appendix A. Housing Fenced area required. No roof needed. Area Dedicated space for racks (19, 2 m high), requires m 2. Gas types and supply lines Supplied from the EHN1 general infrastructure: Neutral gases and premixed: Ar, N2, CO2, He, CF4, SF6 and three reserved for Xe, Ne, premixed or other expensive gas. Hazardous gases (and mixtures): ic4h10, CH4, Ar/H2 and two reserved for other flammable gases or premixed gases containing flammable gas. Neutral gas distribution (arrival from the gas hut): two gas distribution panels will be installed in the gas mixing zone. Each panel will contain five gas types (CERN standard panel for neutral gas ). Flammable gas distribution (arrival from the gas hut): one gas distribution panel will be installed in the gas mixing zone. It will contain five gas types (CERN standard panel for flammable gas ). All gases will be connected to automatic change-over panels based on pressure measurement. If possible, for gases that are liquid at ambient temperature, the change-over mechanism will be driven by the weight otherwise the modification will be implemented in a second phase. Gas mixing/ monitoring At full capacity the gas mixing zone will contain about 6 mixing racks, 3 closed loop gas systems, 2 analysis racks and one control rack.

10 Page 10 of 14 Gas analysis for flammable mixtures: One infrared analysis rack with several (at least three) gas channels in order to monitor permanently the flammable gas concentration in non-flammable mixtures. For each channel a hardwired interlock signal will be available in order to stop the corresponding mixer when required. Gas distribution Gas (mixture) distribution: a typical gas distribution panel contains 4 supply (outer diameter 8 mm) and 4 return (outer diameter 10 mm) channels. The gas distribution is divided in panels for neutral mixtures and panels for mixtures that might contain flammable gases. 6 panels for neutral and 6 panels for hazardous gases are needed to supply the bunker zone. Each 4 panels will also be equipped with 3-way valves additionally supplying the preparation zone. Gas piping Gas piping should be in stainless steel cleaned following standard CERN cleaning procedures. Table 7: s of the gas zone 6. COUNTING ROOM Dimensions Electricity Ethernet Users signals/hv WLAN 2 typical EHN1 control rooms with each about 15 m 2. Sufficient space to host several work places with PCs and a few standard 19 racks. For several electronic racks and computers. 10 outlets per room Patch panel for the arrival from the preparation/bunker zone CERN standard covering the control rooms Table 8: s of the counting hut 6.1 CONTROLS AND LOGGING SYSTEM Beam steering and monitoring Detector Control System (DCS) Monitoring and logging system EHN1 standard including SPS timing signals and experimental scalers. The environmental and radiation sensors, the relevant parameters of the gas system and the source status are monitored. Monitoring and logging of source status and other relevant irradiator parameters like status of the particle beam, exposure status of the source, present attenuation values (positions of the lead attenuators), measured dose rates, running time and environmental data by facility control system. Information to users by when the source status changes. Part of the information will be made available on a central CERN service such as TIMBER. Table 9: Controls and monitoring parameters

11 7. USER S EQUIPMENT FOR TESTING REFERENCE EDMS NO REV VALIDITY Page 11 of 14 Large equipment to be placed in the preparation and the irradiation areas are primarily detectors of all types. Additionally one could imagine the placement of an electronic rack or similar, where the space management has to be done on the fly. Weight Dimensions Single pieces of maximum 5 tons Maximum 6 m by 3m x 1m (orientation not pre-determined); a free height of 4.8 m above false floor shall be guaranteed for placing users equipment. Floor load Designed for a maximum load of 8 T distributed on 4 feet. Local stresses cannot exceed 2000 kg per foot of at least 10 cm x 10cm. The distance between two feet has to be at least 1 m. Transport Possibility to transport users equipment between outside and preparation area and between preparation area and bunker. For heavy equipment the EHN1 overhead crane can be used (maximum load 80 T). Between preparation area and bunker the transport of users equipment up to 2.5 tons should be possible using a transpalette/ pallet carrier. Table 10: Specifications of tested equipment and transport requirements 8. IRRADIATOR At the time of writing this document, the source tender is on-going. The earlier market survey can be found in [6]. 8.1 IRRADIATOR LAYOUT The items relevant as requirements to the GIF++ layout are summarized in Table 11. Source material Source activity Dimensions Weight Shielding Photon windows Caesium 137 isotope ( 137 Cs) 16 TBq ±10%, photons typically at 662 kev Maximum 1 m x 1 m x 2 m (footprint times height) about 3 tons Provided by supplier. Parking position: fully contained inherently failsafe Opposite 180 o, each with an opening ±37 O horizontal/vertical Table 11: Irradiator properties 8.2 IRRADIATOR INSTALLATION The irradiator is remotely controlled and will be delivered with its own control system. The source safety system and redundant interlock interfaces (for access, alarms) are included in the industrial supply.

12 Page 12 of 14 For an optimum use of the photon field, the source should be moveable between two positions: using the secondary muon beam, the source should be placed as close as possible to the axis of the beam line. In case muons are not available, the source shall be placed in such a fashion that the axis of the source coincides with the centre of the cosmic muon trigger. Displacement Adjustable opening Logging Safety Uniform field field Irradiator together with filter system manually displaceable on rails between the two positions being 1.5 m apart. Both windows can be manually covered with collimators reducing the horizontal/vertical angular spread. Connected to a central CERN service (e.g. TIMBER) For access, emergency (power cut ) Uniform field over the plane of detectors (fluence of non-scattered gammas) in both irradiation zones achieved by two lenses, one upstream and one downstream Attenuated field Radiation monitors Source controls/interlock Filter system of remotely adjustable filters in three slides hosting three different plates of various thicknesses with each weight of less than 200 kg. Allows for large irradiation zone attenuation factors between 1 and in several steps The irradiator will be delivered with three radiation monitors (different from CERN-RP monitors) to be installed inside the bunker. The irradiator will be provided with a controls/interlock service, which shall be connected to the CERN systems of access control and emergency systems. Table 12: s of the irradiator installation 9. REFERENCES [1] CERN, "About slhc," [Online]. Available: [Accessed ]. [2] CERN, "The X5 Irradiation Facility," [Online]. Available: [Accessed ]. [3] M. Capeans, R. Fortin, L. Linsen and M. Moll, "Proposal to the CERN SPSC - A GIF++ Gamma Irradiation Facility at the SPS H4 Beam Line," [4] CERN-DGS RP-TN, "Radiation protection requirements on the access system for the GIF++ facility," CERN, [Online]. Available: [5] B. Biskup, "Studies for GIF++," CERN, [Online]. Available: [6] R. Fortin and F. Ravotti, "Technical Description 137 Cs Irradiator," CERN, [Online]. Available: _Technical_Description.pdf.

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14 Page 14 of APPENDIX A Schema of the gas distribution for the GIF++ facility: The schema should allow the responsible developing a full system. It does not indicate all necessary valves, meters and gas equipment yet.