Beam Secondary Shower Acquisition System FrontEnd RF Design

Beam Secondary Shower Acquisition System: Front-End RF Design Student Meeting Jose Luis Sirvent Ph. D. Student 19/08/2013

1. The dynamic range and the three lines • • • Two or Three lines to cover all the needed Dyn. range (1 -1 e 6 MIPS) Scheme valid for QIE as well as ADC Technique based on splitting the signal (Detector current or Charge -> Voltage) The idea is to use 1 detector and 2 or 3 lines and sample in parallel Profile reconstruction Bunch By Bunch based on the combination of lines

1. The dynamic range and the three lines • Initial proposal of architecture: – – 3 Signal cables (Tunnel – Detector) : 34 d. B, -6 d. B & DC 2 Power supply cables (Tunnel - Detector) 1 Splitting + Amplification in Tunnel 1 Splitting + Attenuation in Surface HV Cividec AC-DC Splitter Diamond Detector p. CVD AC Cividec 40 d. B -6 d. B 12 V DC DC • Amplifier -6 d. B Mini-Circuits DC-4 GHz Splitter 34 d. B -12 d. B The proposal can be Optimized: -6 d. B Mini-Circuits 1. The p. CVD from Cividec has high output impedance DC-4 GHz Splitter RF equipment needs to be well adapted for optimal transmission 2. Line DC could be avoided We can split in surface x 3 and lowpass one output Less Installation needed Tunnel -6 d. B Surface Cividec -6 d. B Attenuator -20 d. B -32 d. B

1. The dynamic range and the three lines • To adapt… or not to adapt? (CK 50) – Better frequency response if adapted in both sides, see green line

1. The dynamic range and the three lines • Updated proposal: – – Lines well adapted Less components in the tunnel (Simpler layout) HV Cividec -6 d. B Diamond Detector DC-4 GHz Splitter p. CVD 40 d. B -6 d. B Termination 50Ω • 34 d. B Amplifier 12 V Tunnel -6 d. B Not yet clear: -12 d. B -6 d. B 1. If DC measurement is necessary then -9 d. B splitter: Needed lines 34 d. B, -15 d. B & -35 d. B DC-4 GHz Splitter -32 d. B Attenuator -6 d. B Surface -20 d. B Low Pass Filter Fc= 5 Hz DC

1. The dynamic range and the three lines • Updated proposal: – – Lines well adapted Less components in the tunnel (Simpler layout) HV Cividec -6 d. B Diamond Detector DC-4 GHz Splitter p. CVD 40 d. B -6 d. B Termination 50Ω 12 V Tunnel -6 d. B Look Out!! Worst case: 1 e 6 MIPS in 1 ns Charge = 1. 6 e 9 C p. CVD peak current =1. 6 A!! Needed to calculate the dissipated power per device and make wise decisions or … 34 d. B Amplifier -12 d. B -6 d. B DC-4 GHz Splitter -32 d. B Attenuator -6 d. B Surface -20 d. B Low Pass Filter Fc= 5 Hz DC

2. Going back to Pspice Model of the proposed Front-End !!!

3. To shape or not to shape • • 1. Shaping is filtering: Band-Pass 2. A correct shaping avoids bunch pile-up (Cable effect): Recover base-line – Criteria: • • • Ti= 1/2 Tbunch (0. 5 e-9 for 1 ns bunches) Fc low= 2 GHz Td= 1/5 Tbetween bunches (5 e-9 for 25 ns spaced bunches) Fc high= 200 MHz 3. Shaping “cleans” the signal: Better SNR Working Freq. Range (200 e 6 – 2 e 9 Hz)

3. To shape or not to shape By using our Matlab GUI: Observations: 1. Shaper returns base-line (Cable independence) 2. Shaper provides better results in fitting sigma with ADC 1. 2. On Mean error: 2. 95 e-3% Off Mean error: 8. 55 e-3% 3. 4. 5. 6. If Shaper used, not possible to use QIE 10 (mean charge = 0 C) QIE 10 results justified by Digitalization scheme (eqr 0. 7 – 1. 4%) When integrating the Pile-Up effect is more evident. Errors maybe too small ( <0. 1% ) for taking a decision. 7. Timing evaluation of ADC’s to see if possible peak detection at 40 Mhz. (Synchronization Issues? ? )

3. To shape or not to shape Peaks Without Shaper Pile-Up: + 0. 01% Integration Without Shaper Peaks With Shaper Pile-Up: - 0. 0004% Integration With Shaper o 0 st end Pile-Up: + 0. 15% et le! g b i r s a s h t po nch c o N bu s n 25

3. To shape or not to shape Example of an Slow shaper: Band-pass 1 e 3 - 2 e 9 Hz Ti: 0. 5 e-9 Td: 1 e-3 Example of an Quick shaper: Band-pass 200 e 6 - 2 e 9 Hz Ti: 0. 5 e-9 Td: 5 e-9 In case of using a shaper this must be quick enough (bunch level) to not modify the Gaussian shape. But remember, If shaper is used not possible to use QIE 10!! • • • Option A (No problem with RH. Amplif) : • • Quick shaper (200 e 6 – 2 e 9 Hz) • Clean signal • No impact on Gaussian profile • Only compatible with fast ADC’s or standard well synchronized Option B (Some developments are needed): • No shaper • ‘Dirty’ signal • No impact on Gaussian profile (if not much noise) • Compatible with QIE 10 and ADC’s