1. 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

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

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

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

13. 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

14. 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