NO n A at Caltech

1. NOnA at Caltech Leon Mualem DOE Review July 25, 2007

2. The NOnA Detector ~80 m • ~16 kT total mass • “Totally Active” granular design • Outstanding ne patternrecognition & measurement 15.7 m • Alternating X and Y views • 12 Extruded PVC Modules per plane • 32 Individual cells per Module, so 384 Cells per plane Working to fit 260M AY$ TPC cap

3. NOnA Tasks • Hardware • DAQ/Electronics Management • APD Testing • PVC Testing • Fiber Testing • Vertical Slice Tests • Software • Framework Development • Subshower Package • Photon Transport simulation • Supernova Sensitivity Caltech Initiated or Responsible for many aspects of NOnA

4. Overview of Detector R&D NOnA • Perform light output tests to understand the components of the scintillator system [Ongoing] • PVC extrusions, liquid scintillator, WLS fiber • Verification of scintillator system performance using a NOnA APD [Ongoing] • Photon production and transport Monte Carlo [Ongoing] • Personnel – Jason Trevor, Leon Mualem + undergraduate

5. NOnA Scintillator System • Each cell an extruded TiO2 loaded PVC tube with ID 60mm x 39mm x 15.7m long • Cells are filled with mineral oil scintillator which is read out at one end with a U-loop WLS fiber running to a multi-pixel APD • Kuraray 0.7 mm WLS Fiber • Light output requirement determined by achievable noise on the APD amplifier.The current estimate of minimum required Light Output is ~20-25 photoelectrons 0.7mm WLS Fiber • R&D at Caltech • Composition of the PVC cell walls • Liquid scintillator composition • Fiber diameter and dye concentration • Fiber position • Integration testing One Cell

6. Interface and Readout Electronics Box

7. 32 Pixel APD Photodetector Array

8. APD Photodetector • Si Avalanche Photodiode • Custom design to match two-fiber aspect ratio • Bare die mounted to PCB via gold bump thermo-compression

9. Scintillator System R&D • Liquid Scintillator • Two competing mineral oil vendors (Parol, Ren) • Competing vendors for additives • Concentration of additives (pseudocumene, PPO, Bis-MSB) • PVC Extrusions • Three competing PVC formulations (Prime, Aurora, NOvA collaboration) • Two types of TiO2 (Anatase, Rutile) • Competing factors (extrudability, reflectivity, structural issues)

10. Test Setup • We are currently using a “NOnA Cell” with internal dimensions 38.5mm x 60mm x 85cm. • Each end of the fiber “U” is connected to an individual pixel on an M16 phototube by 3.5m of 1.2mm clear fiber. • Fibers are held in a fixed position inside the cell by a pair of acrylic “spiders.” (More on this later) • For testing purposes I am using vertical muons from cosmic rays. • The cosmic ray muon telescope consists of two circular discs (~4 cm diam) separated by 14 cm and 1 inch of lead. PMT Scintillating Disc “NOnA Cell” 1.2mm Clear Fiber Lead M16 PMT Box

11. The “NOnA Cell” • The “NOnA Cell” is actually a rectangular aluminum tube which is lined on the inside with the PVC we are testing. “NOnA Cell” PVC 60mm 38.5mm

12. More “NOvA Cell” Pictures

13. Data • Data from each fiber end is collected and plotted separately • Because the rate is low (one event every 150 seconds), data is acquired over a long period of time (>72 hours) in order to obtain a statistically significant sample

14. Results: Scintillator Samples • Three scintillator samples, RenDix 517p, ParDix 517p, and RenAld517p. • Results show a 20% difference in light output between scintillators made with oil from Ren Oil and those made with oil from Parol. • Pseudocumene from different suppliers appear to perform similarly. • Measurements are highly repeatable.

15. Results: Extrusions • We have tested several extrusion samples. Shown here are our baseline extrusion, our best extrusion made with rutile Ti02, and our best Anatase extrusion. • We have also included two other samples for reference: • A MINOS Strip • The duplicate “NOnA Cell” painted on the inside with BC-620, an acrylic based paint loaded with TiO2(Anatase). • All measurements were performed with RenDix 517P • Initial results show we can do better that the minimum light output specification. Minimum Spec.

16. Upgraded Test Setup • Increased trigger sizes.More than triple the rate, no effect on precision. • Testing apparatus is otherwise unchanged • Increased throughput of system; limited by sample preparation time,instead of trigger rate. PMT Scintillating strip Actual NOnA Cell 1.2mm Clear Fiber Lead M16 PMT Box

17. Extrusion tests

18. More Extrusion Results • Tests of recent extrusions show high and consistent light output compared to previous recipes. • Recent extrusions have also extruded well mechanically.This is CRITICAL to integrity of the detector: — the PVC is the structure

19. Caltech Mini Mini Tracker 16.4 cm 1” Lead 30 cm Minos Scintillator Trigger FRONT VIEW 60cm 40cm 150ppm 1 2 3 4 300ppm SIDE VIEW N N 250ppm Minos Scintillator Trigger “N” = Near length fibers

20. Actual Device • Not as photogenic, but: • Uses prototype APD • 33.4m fiber (Actual length) • It works

21. 300 ppm results

22. Far Light Output vs. Concentration

23. Measurement Summary • 150 ppm • 24 pe’s • Significant spread, 20-35 • 250 ppm • 22 pe’s • Very small spread (only 2 samples) • 300 ppm • 35 pe’s • Range: 30-40 • 3 with ~10% spread

24. NOnA Software at Caltech • We developed a set of light weight libraries (“SoCal”) to allow people to access NOnA data and information in C++/ROOT. • SoCal consists of: • Data format for NOνA • NOvA geometry and electronics connection map • Event display package • Detector & Electronics response simulation tools • Full (and up to date) documentation. • Tools to help people write further packages. • Used by the collaboration to develop reconstruction and analysis used for TDR SoCal Caius Howcroft

25. Event Display Branding Event Source Decay chain Colour = energy deposited Reco'ed event True Hits e/μ π p Caius Howcroft

26. Caltech Reconstruction:“Subshower” Code [HZ, CH] “Raw Data” • 3D shower & Track-like feature reco. • Now the standard in MINOS • Has been applied to NOnA • Preliminary use by Bob Bernstein at Fermilab shows significant signal/background separation • Needs to be carried through to a complete analysis [e.g. Patterson] Sub Showers Caius Howcroft

27. Detector Simulation • Detector simulation code that models the light output of the scintillator, the collection of WLS fiber and the propagation to the APD, “PhotonTransporter” • Tracks individual photons and correctly deals with wavelength dependent absorption, reflection and emission coefficients. • Has been used to understand results from the Caltech test-stand and in production MC. • Accurately reproduces features of measured light collection in a cell Charged Particle WLS Fibers Photon Caius Howcroft Simulated Cell

28. Simulations of Light Output vs. Position

29. Fiber Position Results • Light Yield Simulation suggests light output decreases as fibers approach walls • Effect seen in test stand data, but magnitude smaller than predicted • Tune simulations with data to reproduce changes quantitatively

30. Background Studies • NOnA is a search for a small signal • Understanding and correctly modeling the background is important • Work at Minnesota demonstrated the need for an overburden • This work also showed potential for Supernova detection with the overburden • Additional effort needed to determine sensitivity, and computing requirements to search for small signal events

31. NOvA Electronics Find the SuperNOvA ~15min of data With typical ~10s supernova signal 1s time bins NO OVERBURDEN

32. Find the SuperNOvA ~15min of data With typical ~10s supernova signal 100ms time bins 1m OVERBURDEN

33. Software / Analysis • Created the Framework used for NOvA software development and TDR analysis • This base now being expanded to add features • Created the Subshower analysis package for MINOS, ported to NOvA framework • Showing promising results by Bernstein@FNAL • Needs to be carried through to a complete analysis • Created Photon propagation code • Generally useful for understanding light collection and detector performance • Validation with actual test data continues

34. Caltech Work on NOnA • WLS Fiber R&D • Examined the effect of fiber diameter on light collection in the NOnA geometry (The reduction to 0.7mm WLS Fiber saved $3 million+) • Measured light output for fibers with varying fluor concentration, ongoing optimization • Examine the effect of fiber position inside the NOnA cell on light collection, ongoing input to simulation • Optical Readout System • Verify scintillator system performance using the NOnA APD, original and prototype versions • Quantify results of production variability using different plastic samples, many cells and fibers • Gain experience using the new NOnA APD in small scale prototype modules

35. Summary • NOnA • Caltech has taken a leading role in NOnA detectorhardware R&D • Measurements done thus far at Caltech have been, and continue to be instrumental in the detector design process • We will continue to make contributions central to the detector development effort throughout the next year • We will continue to define the detector performance and identify unique capabilities, such as supernova detection • The arrival of Ryan Patterson will add considerable strength, allowing us to build on our founding roles in NOnA software and analysis