SLIDE 1 Primary Proton Beam Profile Monitors
- Segmented Secondary Emission Monitor-
Outline Introduction Beam test at the KEK-PS Neutrino Beamline Summary
SLIDE 2 Introduction
High intensity proton beam induces large radiation dose. Low material, long lifetime, easy to be maintained Dynamic range : Applied to beam intensity in the beginning
- f experiment. (1012 ～1014 protons/pulse)
Desired Performance of profile monitors at the J-PARC Neutrino beamline Profile measurement resolusion required about 1~2mm. (In case of SSEM, movable structure will be required.)
SLIDE 3 Principle of SSEM
J-PARCでのビームに対応 するため、 SEM (Secondary Emission Monitor)
anode cathode High vacuum
Beam
anode wire/strip
e- e-
Secondary electron signal
Cathode電極の材質と 形状 などを検討。
SLIDE 4
Compare the difference of signal intensity among 5 cathode materials. Check the basic response of SSEM with K2K proton beam (~6x1012 protons/pulse) Materials of cathode Al Cu Ti Cu-Be W
SSEM - Beam test : Purpose -
Requirement for SEM cathode materials we carried out the beam test at the K2K neutrino beamline. Low amount of materials interrupting the beam High efficiency of the secondary electron emission Resistant to heat and sputtering Etc…
SLIDE 5
SSEM - Beam test : Setup -
Cathode Anode 1.5cm 10X10cm Width of strip = 1.5cm. Beam size : vertical size ~4cm Al Placed alternatively at intervals of 7mm. : horizontal size ~2cm require several nC/channel.
SLIDE 6
～150m、 Twisted pair cable To Arc To 1st dump K2K-PS 12GeV proton beam Oscilloscope/ ADC ～1e-06 Torr Vacuum Chamber
SSEM - Beam test : Setup -
SLIDE 7
100 200 300 200 400 600 800 anode voltage [V] signal pulse height [mV]
anode voltage dependence of the signal height Fig : Cu : ch2(center) pulse height Confirm one basic response : Signal height was saturated around 100V. Hereafter, we set the anode voltage to be 200V. Beam Intensity : ～4.3e+12 ppp
SSEM - Beam test : Basic responses -
SLIDE 8 SSEM - Beam test : Basic responses -
Vacuum: ～1e-06 Torr Anode voltage 200V Measured signal wave form (oscilloscope)
1 2 3 4 [µsec] SEM used in K2K (Al:7µm , 5 foils) Al:ch1 Al:ch2 Al:ch3 Reference, Trigger
50mV 1.0V 1 scale 1 scale 9 peak structure can be seen. （ K2K beam: 9bunch/1pulse)
SLIDE 9 1 Y Al Cu Ti Cu-Be W ch1 ch2 ch3 1 1 relative Intensity
Change the beam position from lower to upper. Beam position upper the lower ch. Figure shows the relative intensity to the highest channel in each material. Beam profile does not depend on the cathode materials. In the measured profiles, there are clear response to the beam positions.
SSEM Beam test : Basic responses -
the upper ch. lower center Beam position Beam position
SLIDE 10 SSEM - difference in cathode materials -
20 40 60 80 100 1 2 Al Ti Cu Cu-Be W atomic number Z Secondary Emission Efficiency relative (Cu=1)
Secondary emission efficiencies for the different cathode materials.
■： result of the 70MeV electron beam experiment at SLAC.
All measured secondary emission efficiencies are in the same order. Tungsten is 4 times larger than aluminum in interaction length. Light materials, like Al ,Ti, are preferable. NIM 39 (1966)p.303
SLIDE 11
Ti strip(2mm幅) 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。
SSEM - test of fine segmented cathode -
SLIDE 12
σx ~ 6.4 [mm]
SSEM - test of fine segmented cathode -
SSEMの1mほど手前の SPICでのプロフ ァ イ ル
Preliminary
σx ~ 8.1 [mm] SSEMでのプロフ ァ イ ル
SLIDE 13
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. like Ti strip(2mm). We test the fine segmented cathode electrodes, Beam profile appeared to be measured. We need more detailed study.
