# Conclusions: The Design of the ZEUS regional first level trigger box and associated trigger studies

Chapter 10

Conclusions

The performance of the ZEUS FLT has been investigated for a range of physics of interest, with special regard to the use of data from the tracking detectors. The motivation throughout this work has been to investigate the means by which signal events may be efficiently be selected by the trigger while at the same time holding leakage of beam-gas events through the trigger to a minimum. It has been shown that the RBOX will be able to successfully combine data from the FTD and the CTD in such a way as to further this aim despite the differing geometries of these two detectors.

The most important area of physics at HERA is the study of the proton structure function via the analysis of DIS NC and CC processes. An efficient trigger performance for these events is therefore essential. For this reason, the performance of the RBOX has been optimized with respect to them. The performance of the CTD alone for these events has been shown to be good which meant that it was difficult to further improve the situation. Nevertheless, it has been shown that the RBOX will be able to reduce the loss of CC events by a factor of two within the same beam-gas leakage constraints as placed on the CTD. This should greatly enhance the quality of measurements made.

While the performance of the RBOX has been shown to be good for DIS events, it is important not to lose sight of other areas of physics interest. With this in mind, other processes have been simulated with a view to examining performance in more broad terms. In particular, an investigation of heavy flavor pairs both with and without the influence of initial state gluon bremsstrahlung has been made. This has shown that transverse energy and charged multiplicity are the deciding factors which control the efficiency with which a type of event will be accepted. Also it has been shown that the effects of gluon bremmstrahlung may lead to significant changes in event characteristics for charmed pair events. Most importantly, it is now known that the RBOX will provide a good efficiency for heavy flavor events without the necessity to re-optimize the trigger parameters as designed for DIS.

Further, the efficiency of the RBOX for J/ψ events has been shown to be good. As was mentioned in the introductory chapter, these events will have a scattered electron at a very low angle. These two facts raise the prospect of using the electron calorimeter of the luminosity monitor to make precise measurements of the scattered electron which in turn will permit ZEUS to probe the gluon distribution in a kinematic domain which is completely inaccessible to other machines.

Accurate knowledge of a trigger efficiency is as important as boosting that efficiency. It has been shown here that the full kinematics of a CC event need not be considered when measuring the kinematic dependence of CTDFLT efficiency. This has allowed a picture to be constructed of the likely variation of efficiency which is comprehensive in terms of range. Also, much greater precision has been obtained than would be possible within available computer resources using another method.

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References

[1] A J G Hey, I J R Aitchison. Gauge theories in particle physics. IOP publishing ISBN 0-85274-328-9, 1989.

[2] S L Glashow. Towards a unified theory: threads in a tapestry. Rev. Mod. Phys. 52 539, 1980.

[3] A Salam. Gauge unification of fundamental forces. Rev. Mod. Phys. 52 525, 1980.

[4] S Weinberg. Conceptual foundations of the unified theory of weak and electromagnetic interactions. Rev. Mod. Phys. 52 515, 1980.

[5] P W Higgs. Broken symmetries and the masses of gauge bosons. Phys. Rev. Lett. 13 508, 1964.

[6] I S Hughes. Elementary particles. Cambridge University Press ISBN 0-521-27835-x, 1985.

[7] G Ingleman et al. Deep inelastic physics and simulation. Proc. HERA workshop, Vol. 1, p3, 1987.

[8] G Wolf. Hera: Physics, machine and experiments. Lectures given at Advanced Study Inst. on Techniques and Concepts of High Energy Physics, St. Croix Inst. (1986) 375, 1986.

[9] D Jones, E L Berger. Inelastic photoproduction of J/ψ and γ by gluons. Phys. Rev. D 23 1521, 1981.

[10] J J Aubert. Measurement of J/ψ production in 280 GeV/c μ+ iron interactions. Phys. Lett. B 89 267, 1980.

[11] R Baldini Celio et al. Observation of the reactions e+e → π+ π γ, μ+ μ, γ, a test of Weizsácker-Williams approximation for virtual electrons. Lett. Nuovo Cim. 27 283-288, 1980.

[12] W J Stirling, A D Martin, C-K Ng. Inelastic leptoproduction of J/ψ as a probe of the small-x behavior of the gluon structure function. Phys. Lett. B 191 200-204, 1987.

[13] E Reya, M Gluck, E Hoffmann. Scaling violations and the gluon distribution of the nucleon.

[14] R J Cashmore et al. Exotic phenomena in high energy ep collisions. Phys. Rept. 122 C 275, 1986.

[15] N Harnew et al. Experimental signatures for leptoquark and leptogluon production at Hera. Proc. of the HERA Workshop Vol. 2, p829, 1987.

[16] ZEUS Collaboration. The ZEUS detector: Status report. 1989.

[17] K Long et al. Zeus CTD parameters issue five. Revised ZEUS Note 89-023, 1989.

[18] F F Wilson. The design and optimization of the ZEUS central tracking detector. Ph.D. Thesis, University of Bristol, 1989.

[19] Motorola Ltd. Dsp56000/56001 digital signal processor user’s manual.

[20] N Harnew et al. Vertex triggering using time difference methods in the ZEUS central tracking detector. Nucl. Instrum. Methods A289 290-296, 1989.

[21] C B Brookes et al. Development of the ZEUS central tracking detector. Nucl. Instrum. Methods A283 477, 1989.

[22] V Commichau et al. A transition radiation detector for pion identification in the 100GeV/c region. Nucl. Instrum. Methods 176 325-331, 1980.

[23] T Kinnel et al. Simulation of the ZEUS calorimeter first level trigger. ZEUS Note 90-056, 1990.

[24] A Dake et al. Pictures of events surviving the first level trigger. ZEUS Note 90-033, 1990.

[25] G Anzivino et al. First level trigger for elastically scattered protons. ZEUS Note 90-029, 1990.

[26] H Uijterwaal, S de Jong. Zeus first level trigger rate estimates for beamgas using canonical discriminant analysis. ZEUS Note 89-070, 1989.

[27] W H Smith et al. Global first level trigger timing. ZEUS Note 90-011, 1990.

[28] T Hasegawa et al. Re-estimation of FLT rate with calorimeter and CTD information. ZEUS Note 90-046, 1990.

[29] K Tokushuku. Lists of compound trigger-1 data. ZEUS Note 89-029, 1989.

[30] K Tokushuku. GFLT design document i. ZEUS Note 88-098, 1988.

[31] B Foster, G P Heath. A proposal for ZEUS first level trigger timings. ZEUS Note 87-051, 1987.

[32] G P Heath. Dead time due to trigger processing in a DAQ system with multiple event buffering. Nucl. Instrum. Methods A278 431-435, 1989.

[33] W H Smith et al. Zeus calorimeter first level trigger. ZEUS Note 89-085, 1989.

[34] W H Smith, W Sippach. Status of the calorimeter trigger for ZEUS. ZEUS Note 87-021, 1987.

[35] S K Park, R Seidlein, C J Rush, B Bylsma. The fast clear system for ZEUS trigger. ZEUS Note 89-072, 1989.

[36] B Bylsma et al. Monte carlo studies of the level 2 fast calorimeter trigger. ZEUS Note 89-087, 1989.

[37] W H Smith et al. The ZEUS trigger system. ZEUS Note 89-084, 1989.

[38] Lecce Bologna, Frascati. Triggering on forward muons in Zeus. ZEUS Note 87-060, 1987.

[39] M Adamus et al. Veto wall readout and trigger system. ZEUS Note 87-060.

[40] B Machowski, A Dwurazny. Luminosity monitor and small angle electron trigger DAQ system. ZEUS Note 88-014, 1988.

[41] H Uijterwaal, V O’Dell. Status of the gsltb. ZEUS Note 90-045.

[42] H Uijterwaal et al. Layout of the gsltb. ZEUS Note 89-073.

[43] H Uijterwaal et al. Gslt-the Zeus global second level trigger. ZEUS Note 89-062, 1989.

[44] R C E Devenish et al. The Zeus central tracking chamber second level trigger. 14th Int. Symp. on Lepton and Photon Interactions, Stanford, CA (OUNP-89-19), 1989.

[45] R C E Devenish et al. Geometry and resolution of the ctd slt. ZEUS Note 90-078, 90-078c, 1990.

[46] J M Butterworth et al. Simulation of the ctd second level trigger. ZEUS Note 91-072, 1991.

[47] B Foster, G P Heath. Ctd second level trigger architecture. ZEUS Note 87-076, 1987.

[48] D M Gingrich. Ctd second level trigger software design. ZEUS Note 91.

[49] J B Lane, D M Gingrich, D Shaw. Segment finding in the ctd second level trigger. ZEUS Oxford 89-001, 1989.

[50] S J P Smith. Track finding in the ctd second level trigger. ZEUS Note 90-060, 1990.

[51] C A R Hoare (ed.). Occam 2 reference manual. Prentice Hall International Ltd ISBN 0-13-629312-3, 1988.

[52] R C E Devenish et al. Zeus central tracking detector second level trigger and readout architectures. ZEUS Note 90-048, 1990.

[53] H V D Lugt et al. Transputer network for calorimeter readout and calorimeter second level trigger. ZEUS Note 90-014, 1990.

[54] H Uijterwaal, S Bentvelsen, I Siccama. First and second level trigger cuts for beam-gas suppression. ZEUS Note 90-116, 1990.

[55] J M Pawlak, J Milewski. The design of the bac slt/evb transputer network. ZEUS Note 90-123, 1990.

[56] F Benard et al. Zeus third level trigger monte carlo studies. ZEUS Note 91-050, 1991.

[57] M Crombie et al. Third level trigger interfacing. ZEUS Note 90-116, 1990.

[58] D Bandyopadhyay. Control software for zeus third level trigger system. ZEUS Note 90-037, 1990.

[59] S Bhadra et al. The zeus third level trigger system. ZEUS Note 89-051, 1989.

[60] R Halsall et al. The zeus central tracking detector first level trigger processor. IEEE Transactions on Nuclear Science 37 No. 6, 1990.

[61] G P Heath et al. Design of the ctd first level trigger trackfinding processors. ZEUS Note 89-118, 1989.

[62] Xilinx Inc. The programmable gate array data book. 1988.

[63] B Foster, G P Heath. Private communication.

[64] A Mass, J Biltzinger, B Diekmann. The forward tracking detector in the first level trigger of the zeus experiment. ZEUS Note 91-035, 1991.

[65] A J Martin. Private communication.

[66] A Mass. Customer requirements for the ftdflt electronics. Private communication.

[67] Y Iga, G F Hartner. Zeus trigger monte carlo program status. ZEUS Note 90-084, 1990.

[68] H Uijterwaal (ed.). Zgana1.x, analysis tool for zeus trigger monte carlo events. Private Communication.

[69] M Maire, A C McPherson, P Zanarini, R Brun, F Bruyant. Geant 3 user manual. CERN Data handling division.

[70] T Sjostrand, H U Bengtsson, G Ingelman. The lund monte carlo programmes. Comp. Phys. Comm. 34: 251, 1985.

[71] P Palazzi, R Brun, I Ivanchenko. Hbook histogramming, fitting and data presentation package. CERN Data handling division.

[72] C Vandoni, P Zanarini, R Brun, O Couet. Paw physics analysis workstation. CERN Program Library Q121, 1989.

[73] J Zoll, H J Klein. Patchy reference manual. CERN Program Library, 1983.

[74] J Zoll. Zebra user guide. CERN Data handling division Q100.

[75] D Johnson. The ua5 high energy anti-p p simulation program. Nucl. Phys. B291: 445, 1987.

[76] E Stenlund, B Nilsson-Almqvist. Fritiof version 1.6. Comp. Phys. Comm. 43:387, 1986.

[77] P Palazzi, S M Fisher. Using a data model from software design to data analysis. Proc. Conf. Computing in High Energy Physics, 1989.

[78] Digital Equipment Corporation. Guide to DEC/VAX module management system. 1990.

[79] Tofte Frodesen, Skjeggstad. Probability and statistics in particle physics. ISBN: 82-00-01906-3, 1979.

[80] H Uijterwaal, S de Jong. First level trigger cuts based on the analysis of the zg311t6 monte carlo data. ZEUS Note 90-003, 1990.

[81] F F Wilson. Optimisation of the tracking detectors’ first level trigger using functional discriminant analysis. ZEUS Note 91-077, 1991.

[82] G A Schuler. Heavy flavor production at Hera. Nucl. Phys. B 299 21, 1988.

[83] T Sjostrand, M Bengtsson. Comp. Phys. Comm 43 367, 1987.

[84] L Stanco, G Abbiendi. A new heavy flavor generator in e-p collisions. DESY 90-103, 1990.

[85] L Stanco, G Abbiendi. Heavy flavor production at Hera. Simulation with a new monte carlo event generator. DESY 90-112, 1990.

[86] B R Webber, G Marchesini. Simulation of qcd coherence in heavy quark production and decay. Nucl. Phys. B330 261, 1990. 119

[87]

[88] S M Tkacyzk et al. Inclusive J/ψ production and measurement of the low-x gluon distribution of the proton. Proc. of the HERA Workshop Vol. 1 p265, 1987.

[89] J F Owens. An updated set of parton distribution parametrizations. Phys. Lett. B 266: 126-130, 1991.

[90] J Biltzinger et al. First level trigger concept including low-et physics at zeus. ZEUS Note 91-051, 1991.