1. May 14th 2004RD42 collaboration meeting1 Results with a CVD diamond at the K2K beam-line Jun Kubota(Kyoto Univ.) RD42 collaboration meeting May 14 th 2004 Contents1.Introduction 2.Set up 3.Results4.Summary

2. May 14th 2004RD42 collaboration meeting2 Kyoto Univ. J.Kubota, K.Nishikawa, T.Nakaya, M.Yokoyama J.Kameda(now, ICRR) KEK TRIUMF Toronto Univ. Japan Canada P.Kitching, A.Konaka J.F.Martin, W.Trischuk(RD42) Member

3. May 14th 2004RD42 collaboration meeting3 1.Introduction 1.1 J-PARC neutrino oscillation experiment(T2K) ~1GeV beam J-PARC 50GeV PS Super-K: 22.5 kt Plan to start in 2009 Discovery of oscillation Precision measurement of oscillation parameter

4. May 14th 2004RD42 collaboration meeting4 In a long baseline neutrino oscillation experiment, it’s necessary to monitor the direction, the profile and the intensity of the neutrino beam. 1.2 motivation on spill-by-spill basis The neutrino beam can be monitored on spill-by-spill basis by measuring the secondary muons coming from pion decay A muon monitor is needed (In K2K, silicon pad detectors and ion chamber are used as muon monitors) proton Target

5. May 14th 2004RD42 collaboration meeting5 1.2 motivation(cont.) In T2K long baseline neutrino oscillation experiment, the muon beam intensity is expected to be 1000 times more than K2K In K2K, aboutIn T2K, about Radiation hardness Radiation hardness for silicon detectors will become a problem Test whether a diamond detector is useful as a muon monitor - A diamond detector is installed to K2K muon monitor

6. May 14th 2004RD42 collaboration meeting6 1.3 diamond detector Developed by RD42 2 diamonds bought from Ohio State Univ. -One packaged at Toronto, sent to KEK -Second one still at Toronto Characteristic -Size 0.95cm 0.95cm -Thickness 500 Capacitance 9.1pF(as capacitor)

7. May 14th 2004RD42 collaboration meeting7 2 Set up 2.1 The position of the diamond detector K2K neutrino beam line 200 m silicon detectors ion chamber 3.5m Beam dump Target p 12GeV PS K2K muon monitor Muon intensity @ beam center ; ~ Beam has 9 bunches for 1.1, every 2.2sec

8. May 14th 2004RD42 collaboration meeting8 2.1 The position of the diamond detector(cont.) 35cm Beam center diamond detector silicon detectors ion chamber silicon detectors We install the diamond detector around the beam center The signal from the silicon detector is used as a reference  We don’t know the absolute muon flux Inside of K2K muon monitor

9. May 14th 2004RD42 collaboration meeting9 HV supply Diamond detector 9.1pF capacitor 2200pF (to keep bias voltage) about 20m 50 resistance read out w/o Amp Time constant…about 0.46nsec Operate at the bias voltage of 650V 2.2 Circuit

10. May 14th 2004RD42 collaboration meeting10 Beam spill has 9bunches for 1.1 3mV 1.1micro-sec 2.3 Raw signal from the diamond detector 9 bunches are clearly observed, but, signal also has overshoot overshoot

11. May 14th 2004RD42 collaboration meeting11 3.Results The relation of the collected charge v.s the electric field The charge collection distance  Physical value defined by RD42 Measured item

12. May 14th 2004RD42 collaboration meeting12 0.2 Electric field(V/ m) 1.0V/ m 1.01.21.400.40.60.8 0.02 0.05 0.07 0.06 0.04 0.01 0.03 0 3.1 The relation of the collected charge v.s the electric field diamond/silicon Above 1.0V/ almost flat In RD42 measurement (NIM.A514(2003)79), reach plateau m consistent

13. May 14th 2004RD42 collaboration meeting13 Beam center 3.2 The charge collection distance 13.8pC(56.69ADC count) silicon detector 160pC(656.1ADC count) average of two silicon detectors measured ratio (diamond/silicon) 13.8pC/160pC… 8.6% pedestalsignal @ m(650V) Measurement of the collected charge

14. May 14th 2004RD42 collaboration meeting14 3.2 The charge collection distance(cont.) Thickness of depletion layer Assumption… the collection efficiency;100% The charge collection distance ( ) The charge collection distance 116.5  Possibly underestimate (>20%) due to overshoot(shown by signal photograph) measured ratio Ratio(diamond/silicon) Generated charge for a mip Size

15. May 14th 2004RD42 collaboration meeting15 Summary With a diamond detector, the signal of muon flux ( ) was observed at K2K muon monitor The relation of the collected charge v.s the electric field  above 1.0V/, almost flat The charge collection distance  116.5 …possibly underestimate (>20%) due to overshoot (shown by signal photograph) -agree with the expectation(typical collection distance should be around 120 ) a diamond detector is useful In T2K, we can conclude a diamond detector is useful as a muon monitor

16. May 14th 2004RD42 collaboration meeting16 Supplement

17. May 14th 2004RD42 collaboration meeting17 Measured charge of the silicon detector Beam center 169pC(693.2ADC count) 151pC(618.9ADC count) 160pC @diamond detector Silicon detector Size… 1cm ×2cm depletion layer… 300micro-meter