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Published byVeronica Singleton Modified over 9 years ago
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Running at Low * and High Lumi Test insertion on 13 October 2011:
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Overview of the Insertions H T B BLM (UFO) 15 h
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Zoom 6 MHz 4 MHz 2 MHz 0 Expected rate in H from SD: L = 1.5 x 10 33 Hz/cm 2 SD ~ 10 mb / side min ~ 3 mm / 7 cm ~ 5 % SD (visible) ~ SD x (1 decade / 6.5 decades) ~ 1.5 mb Rate ~ 2 MHz correct order of magnitude
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Scenario for * = 0.7 m Minimum RP approach compatible with BLMs : V : 14 H : somewhere between 21 (would dump) and 28 (ok) conservatively assume 28 Aim at a faster RP beam-based alignment: right after the collimator setup: TCP @ 4 drive RPs quickly to 6 (except RP 220 H) if the beam edge is not hit, the alignment is known within ± 2 Physics: - large |t| elastic scattering (vertical pots with SD region cut away) : 3.5 GeV 2 < |t| < ~ 6.5 GeV 2 - hard diffraction with CMS: RP 220: D = 83 mm, x min ~ 28 ~ 2.7 mm min = 3 % RP 147: D = 70 mm, x min ~ 28 ~ 14 mm min = 20 % (Is this useful ? Don’t align ?) Trigger: RPs (double arm) x CMS dijet: above 100 GeV: min = 200 GeV / 8 TeV = 2.5 % diff. dijet cross-section: ~ 1 nb rate ~ 1 Hz @ L = 10 33 cm -2 s -1 (V) [mm] (H) [mm](for n = 2.5 m rad) RP 1470.850.50 no reference from 2011 but large beam big tolerance RP 2200.400.095 very small (H) need to align with small steps
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Dijet Cross-Section 1nb 1b1b
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Scenario for * = 90 m (V) [mm] (H) [mm](for n = 2.5 m rad) RP 1470.440.32 no reference from 2011 RP 2200.670.43 use 2011 alignment as first guess Two runs: 1. Alignment and minimum bias physics bunches: 2 coll. + 1 non-coll., with 6 x 10 10 p/b n = 2 m rad Option (a): Full scraping exercise for 24 pots (up to 12 hours) operation with Vertical RP @ 5 = TCP + 0.5 mm) Horizontal RP @ 10 (protected by TCSG @ 6 and TCDQ @ 8 ) Option (b): Faster alignment (without touching the beam) (difficult for RP 147: where to start ?) operation with retraction by additional 2 4 hours data taking: - 2 hours: min. bias with CMS, trigger on T2 + RP(single arm) with 1 bunch - 2 hours: RP trigger alone (single or double arm) with 2 bunches At the end: loss map for qualification for more bunches L = 7.6 x 10 27 cm -2 s -1 / b, = 0.05
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Scenario for * = 90 m 2. Diffractive dijets (DPE) with CMS 156 bunches with 6 x 10 10 p/b n = 2 m rad Collimation hierarchy: Vertical: TCP @ 4.5 , TCSG @ 6 – 6.5 , RP @ 8 – 8.5 Horizontal: in addition TCDQ @ 8 , RP @ 10 Alignment already done fast approach (~ 1 h) Trigger: (RP double arm) x dijet (> 20 GeV): diff. dijet : ~ 0.5 b 3 h data taking ~ 10 nb -1 L = 1.2 x 10 30 cm -2 s -1 / b, = 0.05
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Scenario for * = 500 m Aim at physics near the end of the running season, but optics development earlier in MDs. Technical problem (mitigation possibilities currently being investigated) : Anti-collision switch limits relative Top – Bottom pot distance. Best case for RP 220: T – B > 2 x 7 @ m Worst case for RP 220: T – B > 2 x @ m If no mechanical solution for this year: take data for both diagonals separately
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