IPBPM issues (Limitation of resolution)

Siwon Jang(KNU)

Contents

• The status of IPBPM resolution measure-ments– IPBPM calibration measurements with Y-port sig-

nals– IPBPM resolution measurements with Y-port sig-

nals– The limitation of resolution with Y-port signals

• The IPBPM measurements issues– Static signal and BPF– Ref. cavity BPM resonant frequency matching– IQ phase tuning– Honda electronics gain

3

Calibration run of IPBPM• We performed calibration run under the 0dB to 30dB.

– The used optics was 100 x 1000 beta optics, which optics has 1um level jitter for IPA, IPB, IPC.

– The QDOFF was set to 129.047A of IP waist.– The used method was integration method from #54 to #80 sample numbers.– Also I’ and Q’ does not normalized by Ref_Y signal to compare with Honda san’s pa-

per method.

• The Calibration factor was calculated by (All the signal was inte-grated),

I’ = ( I*CosX + Q*SinX ) [counts], Q’ = ( Q*CosX - I*SinX ) [counts]

Calibration factor = ( Δ I’ [coounts] )/( Δ Mover position [um])

• All the I and Q signal were taken mean subtract calculation.

Calibration run of IPBPM

5

IPBPM A calibration• The integrated calibration factor from 30dB to 0dB shows good ratio to

around 3.162 times for every 10B attenuation case. The fitting line was ex-trapolated from 30dB calibration factor.

6

IPBPMs calibration• The integrated calibration factor from 30dB to 0dB shows good ra-

tio to around 3.162 times for every 10B attenuation case.

7

Resolution calculation: 0dB

• We performed resolution run under the 0dB– The used optics was 100 x 1000 beta optics, which optics has 1um level jitter for IPA,

IPB, IPC.– The QDOFF was set to 129.047A of IP waist.– The used method was integration method from #54 to #80 sample numbers.– Also I’ and Q’ does not normalized by Ref_Y signal to compare with Honda san’s paper

method.

• The Calibration factor was calculated by (All the signal was inte-grated),

I’ = ( I*CosX + Q*SinX ) [counts], Q’ = ( Q*CosX - I*SinX ) [counts]

Calibration factor = ( Δ I’ [coounts] )/( Δ Mover position [um])

• All the I and Q signal were taken mean subtract calculation.

• Predicted position was calculated as follow equation,– Predicted position of IPA-YI’ = a1*IPB-YI’+ a2*IPB-YQ’+a3*IPC-YI’+ a4*IPC-YQ’+

a5*Ref-Y– Residual of IPA-YI’ = Measured IPA-YI’ – Predicted IPA-YI’

20dB calibration 1220 owl shift

0dB calibration 1220 owl shift

10

IPBPM resolution Study

The calibration factor of IPA with 0dB was 4606.66 counts/um.The ADC counts was multiplied 2.5 times for 5V range.

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IPBPM-A resolutionRMS of residual for IPA resolution calculation (RMS = 558.029 counts) :

RMS/(Calibration factor)= 1558.029counts/(4606.66 counts/um)= 121.135nmGeometrical factor x RMS/cal = 66.1048nmMeasured chage/norm charge x Geo X RMS/cal = 30.081nm

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IPBPM-B resolutionRMS of residual for IPA resolution calculation (RMS = 237.626-counts) :

RMS/(Calibration factor)= 237.626counts/(4006.97 counts/um)= 59.3032nmGeometrical factor x RMS/cal = 47.3732nmMeasured chage/norm charge x Geo X RMS/cal = 21.5572nm

13

IPBPM-C resolutionRMS of residual for IPC resolution calculation (RMS = 776.998-counts) :

RMS/(Calibration factor)= 776.998counts/(4607.57 counts/um)= 191.387nmGeometrical factor x RMS/cal = 48.4439nmMeasured chage/norm charge x Geo X RMS/cal = 22.0444nm

14

Beam orbit re-construc-tion

The data set was taken under the 0dB attenuation.

[mm]

The comparison with old IPBPM

• The High-Q IPBPM was achieved 8.72 nm with 0.6 x 1.6nC, which cor-responds to 5.94nm with nominal beam charge. Also the measured residual counts was 22.02 with full BPM output ports.

• If only used Y-port data then the residual counts changed to 69.08 counts, which corresponds to 27.37nm with 0.6 x 1.6nC. Also this value corresponds to 16.43nm with nominal beam charge.

• Therefore, the Low-Q IP-BPM also have a possibility that the resolu-tion can be reduced with full chan-nel calculation.

• The current BPM resolution has limit around 20nm with Y-port so that weexpect if we used full channel sig-nals of IPBPM then we can get more good position resolution with IPBPM.

The IPBPM measurements is-sues

• Static signal and BPF

Static signal with 0dB Elimination of static signalBy using BPF with 0dB

Delay

The IPBPM measurements is-sues

• Ref. cavity BPM resonant frequency matching

Time-dependence of θIQ

The IPBPM measurements is-sues

• Ref. cavity BPM resonant frequency matching

Tuner range: 3~10.5mm, Fre-quency range: 6.386GHz to 6.441GHz (f0: 6.426GHz)We will make table the reso-nantFrequency due to tuner depth.

The IPBPM measurements is-sues

• IQ phase tuning

Figure by N. Blaskovic

IPA(Y) IPA(Y)

Before the phase matchingIQ angle has no time depen-dency

After the phase matchingIQ angle has time depen-dency

The IPBPM measurements is-sues

• Honda electronics gain

Thank you for your attention!