Rikkyo University Murata.lab / RIKEN Rikkyo University Murata.lab / RIKEN Master course 2nd Kentaro Watanbe Kentaro Watanbe PHENIX Colaboration meeting 2012 ＠ Rikkyo University Optical Alignment System for the PHENIX Muon Tracker Optical Alignment System for the PHENIX Muon Tracker 1

In order to achieve better momentum resolution We should correct for these relative movement !! The purpose of the optical alignment system(OASYS) is the real- time monitoring of the relative alignment among the stations. the muon is flyting 15 degrees Alignment for MuTr W physics W signal : 500 μ m 〜 1.0mm MuTr Chamber resolution : 100 μ m During the experiment period Each chamber moves 50 to 300 μ m by the magnetic field or temperature excursion !!!

Optical Alignment System ① The OASYS consists of a light source at station 1, a convex lens at station 2, and a CCD camera at station3. When an individual station moves, the image on the CCD camera moves reflecting the station movement. By observing the position of the light spot on the image of the CCD camera, we can monitor each station’s relative movement. We use a halogen lamp and optical fiber as a light source for the OASYS. Optical fibers guide light from the halogen lamp It is attached on the edge of station1. Seven CCD cameras have been set up to each octant as in a diagram. station1station3station2 OASys CCD →

Optical Alignment System ② 56 OASYS cameras by each arm. total 112 cameras The results of measurement are peak position distributions for 1000 samples obtained within 30 minutes. The typical sharp image and the typical broad image are displayed. The measured resolution is 1.4 μ m for sharp image, and 3.1 μ m for the broad image. Resolution for the CCD camera The typical sharp image The typical brod image resolution is 1.4 μ m resolution is 3.1 μ m capture raw data image 6.6mm 8.8mm OASys determines the center position by Fitting. First, it makes two histograms which are projected image on the horizontal or vertical axis.….

Optical Alignment System North Arm South Arm All camera X direction Normalize vertical (first day opsition) Range : -15[pixel] to 15[pixel], Horaizontal Range : 2010/1/10~2010/4/20 All camera X direction 12 camera broken 3 camera broken

6 Movement of optics Movement of optics X direction Y direction Run9 first of March to end of June 4 month one day Daily fluctuation 10 μ m Fourier transform No Peak Spectrum ! This fluctuation is defined error of long term. I’m focused the movement of the long term. So, I treat daily fluctuation as random noise. it means the error bar of OASys become about 10 μ m

7 Linear Fit the Movement of optics 90 μ m ７0μm７0μm X direction Y direction I think this long term movement as the rotation or translational motion or Monotonic expansion of the chamber by the fixture degradation, land subsidence.

8 Linear fit all camera: North Arm X direction Linear fit all camera: North Arm X direction /1 〜 6/30 (120day)

9 Linear fit : North Arm Y direction Linear fit : North Arm Y direction /1 〜 6/30 (120day)

10 Linear fit : South Arm X direction Linear fit : South Arm X direction /1 〜 6/30 (120day)

11 Linear fit : South Arm Y direction Linear fit : South Arm Y direction /1 〜 6/30 (120day)

12 OASys Vector Map in Run9 OASys Vector Map in Run9 It is real chamber movement ?? North Arm South Arm What do you think this movement ??

collision external point stub point st3 sagitta stub point st2 stub point st1 sagitta = stub point st3 external point ー ※ The external division is defined from 2 stub information (st1&st2). How to define the sagitta Zero Field Run Saggita Analysis We must confirm that OASys parameter can be tracing real chamber movement by another independent tool. It is “zero field run saggita analysis !!” Because, in the zero magnetic field, almost track became straight. It means the sagitta will disturibute around 0.0

Sagitta distribution & miss Alignment zero field cosmic 1st zero field 2nd zero field pp500GeV pp200GeV March May January chamber moving ?? mean March mean May Miss Alignment = mean_March – mean_May > chamber resolution

Muon momentum study pp500GeV momentum [GeV] run condition under 10GeV 97.3% of ALL !! This spectrum is pp500GeV track associated muon momentum distribution (No track cut ). 500GeV ( / ) 97.3%

momentum [GeV] High pt spectrum seems to decrease than pp500GeV. However under 10GeV muon is 98.3%, high pt muon is not sensitive for the residual distribution. Muon momentum study pp200GeV run condition under 10GeV 98.3% of ALL !! 200GeV (961325/945105) 98.3%

Muon momentum study summary pp200GeV pp500GeV momentum [GeV] The residual distribution is based on under 10 GeV muon. The spectrum is same in pp200GeV and pp500GeV. It means the residual from different beam can be compered. And the different of beam is not sensitive 2nd gaussian. pp200GeV pp500GeV 1/momentum [/GeV] Normalized ( 〜 10GeV) 1/p Normalized log scale 1GeV 0.2GeV

18 sample: south octant8 half2

simulation study From zero field cosmic study, we make sure second gaussian component is not based on hadron decay. So, we guess that component will be based on the effect of multiple scattering another momentum. After the last meeting, Oide-san gave me simple multiple scattering root macro. I modified that macro to near real condition. Fist Step : Air volume contribution (fix muon momentum) At first I assumed if 2.0 GeV muon go through between St1 to St3. Then muon is affected by the effect of multiple scattering from air volume. I want to know the final position (St3) is how much spread by that effect. 2GeV muon st1 st3

calculation by hand The multiple scattering is roughly Gaussian for small deflection angles, the projected angular distribution, with a width given by The projected y direction distribution is given South station2 〜 station3 moun momentum : 2GeV x : 160cm air radiation length : 37g ・ cm^-2 air density : →σ = 469 μ m

the result of simulation 2GeV muon The cause of fixed momentum 2Gev, it can be fit with single gaussian. This simulation consistent with hand calculation.

different momentum distribution 1GeV fixed RMS: 939 μ m 2GeV fixed RMS: 470 μ m 5GeV fixed RMS: 188 μ m 10GeV fixed RMS: 94 μ m

different momentum contribution The second gaussian component is appeared !!! Generate muon distribution pp500GeV

Fit 2gaussian simulation data momentum 1 〜 10GeV RChiS=

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South Arm Run9 March Zero field oct 1 half 1 oct 1 half 2 oct 2 half 1 oct 2 half 2 oct 3 half 1 oct 3 half 2

North Arm Run9 March Zero field

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A few octant have asymmetry distribution. It is not first priority to find out this asymmetry source. However, I was able to find out that source by simple correlation study. So, today I would like to talk about this study.

Run9 South March mean position direction ?

Run9 North March mean position direction ?

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Calculation alignment system (Millepede) PHENIX Physics RUN zero field run 1st zero field run 2nd zero field run 3rd few months Meaning OASys Meaning OASys It is important to align relative positions among the three stations, because it affects the momentum measurement. We align position among the three stations using field off run at the beginning of the experiment. However, each station moved μ m during the experiment period. In order to monitor this real-time movement, an optical alignment system(OASYS) has been installed into muon tracking chamber. Optical Alignment System (OASys) The zero field run data taking is less frequent. However, OASys data taking can be 365days. It is meaningful OASYS. OASys data taking Making use of this advantage, OASys send the signal to taking zero field run for Millepede Alignment. Re-Alignment warning!!

The change of Second gaussian component 上記の通り、２つのガウシアンと pol0 でフィッティングを行うと３月のデータと ５月のデータで第２ガウシアンの ratio が変化しているように見受けられる。特に ５月のデータでは、その量が総じて減っている。この理由を考察する事で今まで ハドロンの decay として扱っていた２つ目の component に対して正確に ID する事が 今回の study の目的である。 Run9 March South Oct8 half1 Rchis : 1.82 Run9 May South Oct8 half1 Rchis : 3.07 単純に Fit が上手く決まらないのが原因で第２ ガウシアンの要素が死んだと考えるものの sample 。 Run9 March Norh Oct3 half1 Rchis : 1.24 Run9 May Norh Oct3 half1 Rchis : 170 Fit は上手くいっていて本当に第２ガウシアンのス ペクトルの形が変化したのかもしれない。と思う もの。

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