P0D Update; WbLS Meeting

1. P0D Update; WbLS Meeting • Initial scope tests with SiPM and Cs137 source • Initial Multichannel Analyzer look with borrowed equipment • Comments on measurements of flux x water x-sec rates in ND280 and backscatter corrections. • Other; efforts to get funds for prototype studies that would be done this summer (DOE R&D, Japan-US funds, others?). Walter Toki, Colorado State University

2. Initial Testing with 6x6mm2SiPM at CSU During CSU spring break SENSL blue sensitive SiPM, using CSU charge sensitive amp w/batteries, room temp. Test with purple 410nm LED, nice signal Test with P0D fiber in P0D scint bar, at green 520nm Test with P0D scint bar + Cs137 source, nice signal Next step is with Liq. Scint. And Cs(Tl) crystal and monoenergetic x-ray source SENSL Blue Sensitive SiPM preamp SIPM SiPM response P0D fiber at 520nm LED pulser Scint. Walter Toki, Colorado State University

3. SCOPE TESTS Blue LED, ext. trigged pulse SiPM ~1cm from LED, Bias=19.2v Signal output PHA= ~50mV, 500ns/cm P0D triangle scintbar, Dow Styron 663 W doped with 1% PPO and 0.03% POPOP (blue peaked) with Cs137 source [this has beta decays and 662 KeV x-ray]. Self triggered SiPM ~1cm to end of scint, Bias= 26.4V Signal output PHA= ~400mV, 250ns/cm Walter Toki, Colorado State University

4. Initial Multichannel Analyzer TESTS with SiPM I borrowed a Spectech MCA which accepts 1ms pulse widths. Since the SiPM pulse width was ~250ns, a ORTEC linear amp shaper was also tried. Using a Cs137 source (which includes beta decay an 662KeV K edge x-ray) on the P0D scintillator bar, we can see the shoulder of the events past the pedestal. Next test will use LeCroy QVT. Pedestal w/o source Pedestal w/source Shoulder due to Beta rays and x-rays from Cs137 source Walter Toki, Colorado State University

5. Green points = pedestal Blue points = pedestal + CS137 signal Red = Blue minus Green Using source on SiPM w/preamp + ORTEC shaper + SpecTech MCA Walter Toki, Colorado State University

6. Measurements; NEXT steps 1) Measure #p.e. with SiPMusing conventional liq. scint.+source. with mono-energetic X-ray 2) Measure #p.e. with LAB Vary Height To adjust rate Fused Quartz curvette X ray Co57 500 keV x-ray disk source Test conventional liq. Scintillator or LAB, ~2mm3 Teflon tape to reflect scintillator light LAPTOP Quartz shield USB MCA (F.S.=2.5V) SiPM or storage scope Suitable calibration Scintillator is BC408. Assuming no funds available Yet, we will buy mono-energetic Sources and standard liq. Scints. Walter Toki, Colorado State University

7. Predicting the Physics Improvements with Live Water Target. The P0D has both vertical bar layers and horizontal bar layers. Current measurements use a subtraction method of water-in data minus water-out data. In the P0D we reconstruct CCinc events where vertex is in the P0D and the muon is reconstructed in the TPC1. This provides a fairly high purity signal. True water vertex Existing muon goes into TPC1 m-  True scint vertex with backscatter [estimated to be ~20%]  Brass Water Vert. scint. bars Hori. Scint. bars m- Existing muon goes into TPC1 Walter Toki, Colorado State University

8. Plot of 1st layer (or most upstream hit) of CCinc Events candidates. Data is in black dots and MC (old flux weights) is color bars (true water vtx=blue, true scint. vtx=red). Vertical and Horizontal scint. Bar layers are plotted. If there was NO backscatter, then blue would appear only in vert. layers and red would be equally amounts in the vert. and horz. Layers. We find that about 20% of the events have a backscatter into the next upstream layer. There is significant cross feed (or backscatter) between vert. and horz. Scintillator layers and between water layer and it’s upstream horz. scint. layer. The impact of this backscatter needs to be understood. Walter Toki, Colorado State University

9. COMMENTS: The Current method to determine that neutrino-water interaction is to perform a subtraction of the water-in data minus the water-out data. This method should be free of the backscatter corrections. Currently Raj Das estimates, with run1-4 data, ~2% syst. Errors on flux-water x-sec measurements. If we have a “live” water target and can tag the neutrino-water interaction vertex, but we will have backscatter corrections which can be subtracted out by using the vertical and horizontal layer hits. Suppose the Nwand Ns are true #water and scint. Layer hit and the obs. Hits in water layer, the vert. bar layer, and the horz. Bar layer, as Nw(obs), Nsv(obs), and Nsh(obs) and the backscatter fraction for scint. & water are gs & gw. Nw(obs, water-in)= Nw(1-gw) + gs Ns Nsv(obs, water-in)= Ns(1-gs) + gsNs Nsh(obs, water-in)= Ns(1-gs) + gwNw For water-in data only; Nw=Nw(obs, water-in)+Nsh(obs, water-in)-Nsv(obs, water-in) We see that a live water target measurements that the vert. & horz. layers, that the backscatter can be subtracted out if we measure the water layer hits and the vert & horz scintillator layer hits. In this scheme, only water-in data is needed. Note that water-out data is still needed for neutral current measurements that will have to have a water-out data subtraction. Walter Toki, Colorado State University