BANDGEM Demonstrator: conceptual design and state of the art

BANDGEM Demonstrator: conceptual design and state of the art

Comparison of the conversion efficiency for different geometries

Actual geometry

New geometry

2Electrons extraction

B4C=3mmGAS=1mm4mmVolumetric Simulation (1000 e-) Diffusion ONGood Electron 1000, Out Electron 544Percentage 54.4Volumetric Simulation (1000 e-) Diffusion OFFGood Electron 1000, Out Electron 670Percentage 67

B4C=2mmGAS=2mm2mmVolumetric Simulation (1000 e-) Diffusion ONGood Electron 1000, Out Electron 263 Percentage 26.3 Volumetric Simulation (1000 e-) Diffusion OFFGood Electron 1000, Out Electron 486Percentage 48.6Actual GeometryNew GeometryNew Charge Extraction simulations

OLD SIMULATION PrototypeNEW SIMULATION Demonstrator

IDL&Garfield++ Simulation taking into account the real absorption point of the neutronsUsing a threshold of 120 keV we obtain an extraction efficiency of 70%.Prototype - AchievedDemonstrator - ProjectedLamella Distance 2 mm4 mmB4C/empty ratio on lamellas13Full Lamella System lenght6 cm9 cmLamella Thickeness250 m20 mLamella MaterialAluminium OxideAluminiumOptimal tilt angle7 degrees5 degreesPulse Height Threshold70 keV120 keVCathode geometry10x10 cm2 - SquareTrapezoidalCount Rate Capability10 MHz/cm212 MHz/cm2Gamma Ray Sensitivity5*10-510-7Measured Efficiency @ 1.5 18.5%//Expected Efficiency @ 1.8 21.2%33%Expected Efficiency @ 4 49%64%Front-end ASICCARIOCA 8 channels/chipGEMINI 16 channels/chipPerformance: Prototype and DemonstratorThe BANDGEM umbrella for LOKITotal active area: 647 cm2

337 mm400 mmCathode8Lamellae system96GEM 16GEM 22GEM 32Readout anode26Detector Assembly The cake

Aluminate mylar cathodeLamellas systemTriple GEMReadout anodeThe aluminated mylar cathodeProduction method: The aluminate mylar foil is stretched using the TendiGEM deviceIts vetronite frame is than glued on it using the rad-hard certified glue

Lamellae systemA total of 100 lamellae will be installed in the BandGEM demonstrator

22 mm

351 mm...Each lamella is composed by a front frame, 24 aluminum strips and two columns that protect the strips in the back side of the frame.

96 mm

31

Protection columnsFront FrameAl stripsGlassAluminaLow neutron interactionLow neutron interactionLower density (2.49 g/cm3)Higher density (3.95 g/cm3)Easy to workHard to workFragileStronger than glassCheapExpensivePossibility to reduce the actual dimensionsThe actual dimensions cannot be scaledLamellae frames

6107Holes for align the front frame and the protectionsWeaker point (the horizontal parts will be removed after the installation). Front frame thickness: 1.9 mmSiO2: 71.5%Na2O: 13.9%K2O:0.2%CaO:8.3%MgO:4.4%Al2O3: 1.3%SO3: 0.3%Fe2O3:0.08%The frames will be made using a water cutting machine (high precision/low cost process)MaterialsLamellae system: production methodThe lamellae will be realized using the TendiGEM device. The aluminum foil (thickness=15 m) will be stretched in the TendiGEM, and after the stretching the front frame will be glued on it using the TermoGuss2000 rad-hard glue.

The assembly frame+aluminum foil is then sent to the laser cutting service in order to cut the aluminum and produce in this way the strips and the contacts. The protective columns are than glued on the back side of the frame in order to protect the Al strips and to avoid the formation of conductive paths between the strips due to the B4C coating.The strips are ready to be coated with B4C.

Lamella system: production methodWhen the coating process is finished, the lamellae are ready to be install inside the detector.The lamellae will be sandwiched between 2 trapezoidal alumina or fiberglass frame (one near the cathode, the other near the first GEM foil) which present a pair of pockets for each lamella.

Pair of pockets for the first lamella

When all the lamellae are sandwiched between the 2 trapezoidal frames, they will be glued inside the pockets. At this point all the frames are constrained to the trapezoidal frames, so we can break the horizontal parts of the glass frame and the strips will remain in position. GEM FoilThe GEM foils will be realized at CERN and they will be glued to their frames using the same technique used for the production of the cathode. Each GEM foil will be sectorized in 8 sectors, in order to reduce the possible damage caused by a spark. A total of 3 GEM (triple GEM) will be installed in the detector and the gap between each GEM (Transfer gaps) is equal to 2mm.All the GEM foils will be sandwiched and glued on the upper trapezoidal frame.

Padded AnodeThe anode will be composed by 1024 pads. The the size of the pads is between 7.7 and 137 mm2. The maximum pad size is similar to the one of the nGEM for SPIDER, and we have already tested the low noise level. The PADs is divided into 10 sectors, while the dimension of the PADs is constant along the y-coordinate and equal to 4mm.At the moment only the PADs were designed, while the position of the read-out electronics is still under investigation. The design of the read-out electronic position will be decided after the test of the GEMINI Chip.The anode will be glued on the GEM3 frame, and the gap between the GEM3 and the PADs (induction gap) will be equal to 2mm.

y14Small Area Prototype- for testingIn order to test the technology processes that will be used for the construction of the demonstrator and to validate the numerical simulation as soon as possible, it was decide to made a small scale prototype (active area=10x10 cm2).

115 mm107 mmWith this detector we can test the production method of the lamellae system (it is the same of the demonstrator) and we can validate the numerical simulations. It will be composed by 25 lamellae (all with the same dimensions) and the 10x10 triple GEM system with its cathode will be the same of the actual BandGEM (and of the other 10x10 GEM detectors such as the bGEM) . This should allow the production and the test of the detector up to the end of this year. Future improvements The design of the demonstrator can be further improved in the future. In fact, by using the glass as material for the lamellae frames and a 5-axis water cutting machine (the actual manufacture will buy it during the next year), is possible to obtain an optimized design, with a reduce amount of inert material inside the detector and than a reduce contribution of the scattered neutrons.

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94State of the art Detector Components and MaterialsWe should have all the materials before/immediately after summer holydays in order to start building the 10x10 prototype for testingComponentMaterialProviderCommentLamellaAl Alloys 1200, 1050 (Al>99%), 8079, 8011 (1% Fe)Korff AG (CH)All Alloys orderd in thickness of 15 and 30 mLamella FrameGlassAG Vertec (B)Suggested by F. Sauli, OrderdFrame/Lamella GlueThermoguss 2000Harold Patscheider GmbHStands > 1000C, Rad-Hard (CERN database). Tested up to 400 CGEM FoilsKapton+CopperCERNNeed to be designedGEM Frames & Lam. System FranesFiberglass/GlassMeroni & Longoni (IT)Need to be resistantPadded AnodeFiberglass + CopperArtel (IT)Need to be designedResistor chain + supporting columnsFiberglassArtel (IT)Resistor chain to be decidedCross Section Glass