Study of a Scintillating Digital Hadron Calorimeter Prototype (status and plans) Alexander Dyshkant for NICADD Northern Illinois University (DeKalb, IL 60115) 1/2/2019 Alexandre Dychkant / Arlington LC Workshop

Alexandre Dychkant / Arlington LC Workshop A SAMPLING DIGITAL HADRON CALORIMETER A sampling hadron calorimeter with an excellent resolution (30%/E) for jets is a key point for future linear collider detector. Such a resolution can be achieved by use of an energy flow technique, which associates hadron calorimeter cells with a charged track. The higher lateral and longitudinal segmentation the better should be the association. A highly segmented hadron calorimeter will be very complicated and expensive. A digital approach is a single bit readout for each cell. It can provide a cheaper solution for signal processing, but demands a very fine segmentation of an active part of the hadron calorimeter, which will consist of millions of small cells. 1/2/2019 Alexandre Dychkant / Arlington LC Workshop

68% COMPARISON OF BRIGHTNESS FOR A CAST SCINTILLATOR WITH EXTRUDED SCINTILLATOR Cast scintillator BICRON BC408 Extruded scintllator MINOS strip 68% 1/2/2019 Alexandre Dychkant / Arlington LC Workshop

DESIGN OF AN OPTICAL CELL We studied a hexagon shape, 9.4 cm² area (19 mm side) cell made from 5 mm thick scintillator. A WLS round fiber, with one mirrored end, which was embedded and glued into the cell’s groove, was used as readout. Different groove’s shapes were tested. The straight and sigma groove shapes are the best candidates for building our first prototype Coating of scintillating cell play a key role in determining the light response. We were looking for coating with minimal handling, stable in time, and with high production rate. 1/2/2019 Alexandre Dychkant / Arlington LC Workshop

DESIGN OF AN OPTICAL CELL Even in the case with sufficient amount of light the dead zones and edge effects can significantly reduce the efficiency of particle registration. · The hexagon cell shape provides the shortest perimeter and uniform light response for a given area because in a regular hexagon all angles are obtuse. · Measurements of the cell response using a PMT provides a reliable estimate of efficiency across the entire surface. Uniformity response was measured for the following cell conditions: 1/2/2019 Alexandre Dychkant / Arlington LC Workshop

RELATIVE UNIFORMITY RESPONSE SIGMA GROVE DESIGN OF CELL FOR TRADITIONAL SIGMA GROVE DESIGN OF CELL Scintillator BC408 Thickness 5 mm Area 9.2 cm² WLS fiber BCF92 Round 1.0 mm Sigma groove Width 1.2 mm Depth 2 mm Radius 13 mm 1/2/2019 Alexandre Dychkant / Arlington LC Workshop

A NEW DESIGN OF SCINTILLATING CELL THE SAME PATERN AS EXTRUDED CELL A non full circle sigma groove is cut from the top to the bottom surface of a cell (the depth of the groove is the same as the thickness of scintillator). A WLS fiber needs to be glued inside the groove as a spiral. The mirrored end of the fiber needs to be glued in the bottom of the groove. 1/2/2019 Alexandre Dychkant / Arlington LC Workshop

Alexandre Dychkant / Arlington LC Workshop A NEW DESIGN OF READOUT FIBERS Clear KURARAY fiber 2 m long (round 0.94 mm outer diameter) Ferrule Thermal splicing 25 mm long tube Al mirror WLS Y11 KURARAY fiber 125 mm long (round 0.94 mm outer diameter) 1/2/2019 Alexandre Dychkant / Arlington LC Workshop

MIRROR REFLECTIVITY AND SPLICING TRANSMISSION US CMS BARREL HCALL PRODUCTION RESULTS FOR MIRROR REFLECTIVITY AND SPLICING TRANSMISSION 1/2/2019 Alexandre Dychkant / Arlington LC Workshop

Alexandre Dychkant / Arlington LC Workshop CONTROL M EASUREMENTS OF CELL RESPONSE We’ll build a tower of a sampling calorimeter prototype. It will consist of 12 active layers with at least 7 cells in each layer. 1/2/2019 Alexandre Dychkant / Arlington LC Workshop

DESIGN OF CELL (EXTRUDED) UNIFORMITY RESPONSE FOR NEW DESIGN OF CELL (EXTRUDED) 1/2/2019 Alexandre Dychkant / Arlington LC Workshop

Alexandre Dychkant / Arlington LC Workshop UNIFORMITY RESPONSE FOR NEW DESIGN OF CELL (EXTRUDED) 1/2/2019 Alexandre Dychkant / Arlington LC Workshop

Alexandre Dychkant / Arlington LC Workshop SUMMARY Measurements shows that cells with Y11 KURARAY WLS fiber, spliced with the clear fiber, provide ~40% more light than cells with BICRON BCF92 WLS fiber. Cells, made from extruded scintillator (MINOS strip), provide 68% light output response compare to the cells made from casting scintillator BC408. Uniformity measurements for the new design of cells (extruded pattern) were performed. They show up to 30% less light output in the area where the groove is located. 1/2/2019 Alexandre Dychkant / Arlington LC Workshop

Alexandre Dychkant / Arlington LC Workshop SUMMARY We hope to have ~30 photo electrons from MIP for 80% quantum efficiency photo cathode for the extruded scintillating cell with KURARAY WLS fiber. Future Plans Production of the cells for building a tower is in progress. We have enough cells for 7 layers. We have started cosmic rays measurements to obtain absolute response to a MIP. 1/2/2019 Alexandre Dychkant / Arlington LC Workshop