Primary Proton Beam Profile Monitors -Segmented Secondary Emission - PowerPoint PPT Presentation

Primary Proton Beam Profile Monitors -Segmented Secondary Emission Monitor- Outline Introduction Beam test at the KEK-PS Neutrino Beamline Summary

Introduction Desired Performance of profile monitors at the J-PARC Neutrino beamline High intensity proton beam induces large radiation dose. Low material, long lifetime, easy to be maintained (In case of SSEM, movable structure will be required.) Dynamic range : Applied to beam intensity in the beginning of experiment. (10 12 ～ 10 14 protons/pulse) Profile measurement resolusion required about 1~2mm.

Principle of SSEM SEM (Secondary Emission Monitor) wire/strip anode cathode anode J-PARC でのビームに対応 Secondary するため、 electron Beam Cathode 電極の材質と 形状 e - などを検討。 e - High signal vacuum

SSEM - Beam test : Purpose - Requirement for SEM cathode materials High efficiency of the secondary electron emission Low amount of materials interrupting the beam Resistant to heat and sputtering Etc… Materials of cathode we carried out the beam test at the K2K neutrino beamline. Check the basic response of SSEM with K2K proton beam (~6x10 12 protons/pulse) Compare the difference of signal intensity among 5 cathode materials. W Cu Al Cu-Be Ti

SSEM - Beam test : Setup - 10X10cm 1.5cm Placed alternatively at intervals of 7mm. Al Cathode Anode Beam size : vertical size ~4cm : horizontal size ~2cm � require several nC/channel. Width of strip = 1.5cm.

SSEM - Beam test : Setup - To Arc To 1st dump Vacuum Chamber K2K-PS 12GeV ～ 1e-06 Torr proton beam ～ 150m 、 Twisted pair cable Oscilloscope/ ADC

SSEM - Beam test : Basic responses - anode voltage dependence of the signal height 800 signal pulse height [mV] 600 400 Beam Intensity : ～ 4.3e+12 ppp 200 0 100 200 300 anode voltage [V] Fig : Cu : ch2(center) pulse height Hereafter, we set the Confirm one basic response : anode voltage to be Signal height was saturated around 100V. 200V.

SSEM - Beam test : Basic responses - Measured signal wave form (oscilloscope) 1 scale Reference, Trigger SEM used in K2K (Al:7 µ m , 5 foils) 1.0V Al:ch1 1 scale Al:ch2 Vacuum: 50mV ～ 1e-06 Torr Al:ch3 Anode voltage 200V -1 0 1 2 3 4 [ µ sec] 9 peak structure can be seen. （ K2K beam: 9bunch/1pulse)

SSEM Beam test : Basic responses - Beam position center Al 1 Cu Change the beam position Ti Cu-Be from lower to upper. W 0 Beam position relative Intensity upper 1 Figure shows the relative intensity to the highest channel in each material. 0 Beam position 1 lower In the measured profiles, there are 0 clear response to the beam positions. ch3 ch2 ch1 the the Y Beam profile does not depend on the lower upper cathode materials. ch. ch.

SSEM - difference in cathode materials - Secondary emission efficiencies for the different cathode materials. Secondary Emission Efficiency 2 All measured secondary Cu-Be emission efficiencies W Ti are in the same order. 1 relative (Cu=1) Cu ■： result of the 70MeV electron Al beam experiment at SLAC. NIM 39 (1966)p.303 0 0 20 40 60 80 100 atomic number Z Tungsten is 4 times larger than Light materials, like aluminum in interaction length. Al ,Ti, are preferable.

SSEM - test of fine segmented cathode - 現在、 Cathode 電極を多 ch 化し 、 K2K の DAQ を用いてプロフ ァ イ ル 測定のテスト を行っ ている。 Ti strip(2mm 幅 )

SSEM - test of fine segmented cathode - Preliminary SSEM でのプロフ ァ イ ル σ x ~ 6.4 [mm] SSEM の 1m ほど手前の SPIC でのプロフ ァ イ ル σ x ~ 8.1 [mm]

Summary In this beam test at the K2K Neutrino Beamline We confirmed the basic responses of SSEM. Secondary emission efficiencies are in the same order in 5 cathode materials. � In terms of interaction length, Al or Ti is preferable. We test the fine segmented cathode electrodes, like Ti strip(2mm). � Beam profile appeared to be measured. We need more detailed study.