Analysis of HF optimization scan data 21 July 2015 Monika Grothe (Wisconsin) 1 21 July 2015 HF optimization scan analysis

21 July 2015 HF optimization scan analysis2 Presence of zero values Large spread in non-zero values Visible cross section for HF, fill 3992

For comparison: BCM1F and PLT and Current product 21 July 2015 HF optimization scan analysis3 BCM1F PLT FBCT_B1 * FBCT_B2

Q: Are the HF BCID slots shifted wrt nominal ? Looked at the Y scan of fill 3992, specifically at the central (4 th ) scan point, when beams are heads-on, i.e. lumi measurements should be at maximal values Plots on following pages show the uncalibrated luminosity as function of bcid, averaged over the time window of the 4 th scan point. For better readability, distributed the full bcid range (1 to 3564) over 36 histograms. Full set of histograms can also be found in – /afs/cern.ch/work/g/grothe/public/comp_HF_BCM1F_FBCT/ 21 July 2015 HF optimization scan analysis4

21 July 2015 HF optimization scan analysis5 There appears to be a shift in bcids HF shows double band structure

21 July 2015 HF optimization scan analysis6 There appears to be a shift in bcids HF shows double band structure

Title 21 July 2015 HF optimization scan analysis7 Currents: single non-zero value at bcid 1270 BCM1F: single non-noise level value at bcid 1270 HF: around bcid 1270 just noise HF: non-noise level value double peak at bcids 1307 and 1308

Title 21 July 2015 HF optimization scan analysis8 Currents: non-zero value at bcid 1828 HF: double-peak at bcids 1865 and 1866 From ~1870 onwards, every other bcid has non-noise level value For HF, all bcids after 1870 have non- noise level values

Summary on HF 21 July 2015 HF optimization scan analysis9 BCM1F nicely tracks the FBCT1*FBCT2 current product HF shows a much more complicated pattern: – When the lumi appears to be above noise level, there are two distinct bands. – For isolated bcid with non-zero current, the HF luminosity is above noise at bcid+37 and bcid+38. – The relative height of the two peaks (about ¼ to ¾) points to an average offset of around 37.7.

Some more observations: 21 July 2015 HF optimization scan analysis10

Noise 21 July 2015 HF optimization scan analysis11 Noise shows an exponential decay Then randomizes Afterglow ?

Title 21 July 2015 HF optimization scan analysis12 Noise in BCM1F bcid 500 to 600 bcid 800 to 900bcid 700 to 800 bcid 600 to 700

Title 21 July 2015 HF optimization scan analysis13 Noise in HF bcid 500 to 600 bcid 700 to 800bcid 800 to 900 bcid 600 to 700

Summary on noise 21 July 2015 HF optimization scan analysis14 In the bcids following bunch trains with non-zero currents, both BCM1F and HF show noise: – That decays exponentially and then randomizes – For BCM1F, the randomization appears to take over more quickly than for HF BCM1F noise appears fully random after ~400 bcid For HF noise has not fully randomized after ~ 500 bcid – Noise just after a bunch train with non-zero currents is O(100) lower than the non-noise level lumi values for both BCM1F and HF