The present invention relates to an on-line coating adhesion determination apparatus of a galvannealed steel sheet, and a galvannealed steel sheet manufacturing line. [Related Art] [0002] A galvannealed steel sheet has been used worldwide as a steel sheet for vehicles. The quality characteristics required for the galvar~nealetsl teel sheet include corrosion resistance, coating properties, weldabilit): po\vdering resistance during press forming, and flacking resistance during press forming, and the like. Fe-Zu phases constituting the coating layer of the galvannealed steel sheet include a t; phase, a FI phase, and a-T.TI phase. Among the above-described characteristics, press fonoability palticolarly represented by powdering resistance and flaking resistance is dependent on the amounts of the t; phase and the T.TI phase. The po\\dering resistance is enhanced as the T.TI phase is reduced, and the flaking resistance is enhanced as the t; phase is reduced. Therefore, in order to obtain good press fonnability, a coating layer mainly containing the F1 phase is required. [0003] In order to form the coating layer mainly containing the 61 phase, the coating bath composition (A1 concentration in a bath), the bath temperature of a coating bath, and heating and cooling conditions for alloying need to be optimized depending on the steel components. Typically, the Al concentration in a bath and the bath temperature are maintained in constant ranges, aud rnoreovel; a heating and cooling pattern that is considered to be optimal is determined depending on an alloying rate of the steel for the operation. However, in practice, due to operational conditions in an upstream process (a process before coating) such as hot rolling, the alloying rate may vary in coils even in same type of steel and in paits even in same coil depending on actual operational conditions. Therefore, each time, an operator finely adjusts the heating and cooling conditions \\41ile visually checking the degree of alloying. As a result, \\'hich alloy phase is obtained and whether or not po\vdering resistance and flaking resistance are good are checked by off-line testing and analysis on the representative parts (typically a front portion andlor a tale pottion) of a coil after production. [0004] IElowevet; in the metliod of checking coating quality through the off-line testing and analysis, quick feedback of tlie operational condition may not be achieved. Therefore, for example, in a case where an alloyi~~ragte is changed due to a change in steel type, there is a risk of a reduction in yield. In addition, for example, depending on coiling conditiotts during 11ot mllitig or the like, there !nay be cases where alloying of the front portion of a coil is slower than alloying of the middle portion. In this case, \\(hen tlie operation is performed to meet the alloying condition oftlie fiont portion, tlie middle portion is excessively alloyed, and powdering of most of palls of tlie coil may beco~nea pparent. [OOOS] In order to prevent the problems beforehand, on-line measurement \\,it11 high accuracy over the entire length of tl~eco il is eKective. A technique employed for this purpose is an on-line X-ray diffraction method. An X-ray diffraction method is a method for qualitative and quantitative measurement of crystal phases in a coating layer using the diffraction phenomenon \\~liicho ccurs \\,hen ctystals are irradiated \\,it11 X-rays. In a case where this metliod is used for the on-line measurement, selecting diffracted X-rays having a good correlation between the diffracted X-ray intensity and tlie crystal pliase thickness is necessaly. Furthercnore, in order to obtain high measurement accuracy, selecting diffracted X-rays having a high intensity from a practical diffraction angle range is necessary. [0006] In Patent Documents 1 and 2, as a practical diffraction angle (28) range, 28>80° (in a case where Cr is used as an X-ray target, a crystal lattice spacing is d<1.78A) is disclosed as a range in which effects of flappit~go f a steel sheet, tlle ther~nael ffect of the steel sheet, and a change in incident X-ray intensity are small. As tl~ec~ ystalla ttice spacing which satisfies the above conditions, tllose that are widely used in the past are, for example, as described in Patent Docoments 2 to 5, d = 1.26A (28 = 130" when the target is Cr) for a C; phase, d = 1.28A (28 = 127" \\,lien the target is Cr) for a 61 phase, and d = 1.22A (28 = 139' when the target is Cr) for a r.rl pliase. [0007] However, it cannot be said that the on-line X-ray diffractiot~m ethod according to the related art is sufficient to perfon11 on-line measurelilent over the entire coil length with high accuracy, to quickly feed the results back to operational conditions, and to prevent excessive alloying or non-alloying beforehand. The biggest reason is that the three X-ray diffraction peaks respectively indicated by the C; phase, the FI pliase, and the T.TI phase, \vhich have been used in the past, are adjacent to each other and are present in a region \!.it11 a background that is high and is not flat. In tlie related art, a constraint condition of 28>80° \\4iicli is a range in which the effects of the flappiug of a steel sheet, the ther~nael ffect from the steel sheet, and a change in incident X-ray intensity al-e small, and a condition of simoltaneoos oieasttre~nentc aused by the fact tliat tlie X-ray diKraction peaks of tlie three phases (the < phase, the 61 phase, ant1 the T.f I phase) are adjacent, are considered to be important. As a result, the techoique is extremely insctfiicient for achieving the original object to measure the thickness of each phase with good accuracy. [OOOS] In addition, in recent years, for the enlianceoient in tlie productivity of a manufacturing line or competitiveoess, tlie manufacticring line of the galvannealed steel sheet has beet1 increased in speed. In order to determine the coating adhesion of tlie galvantiealed steel sheet in a high-speed manufactoring lirie on-line, an analysis time for the determination of tlie coating adhesion needs to be reduced. In order to significantly determine the difference between a steel sheet having good coatirig adhesion and a steel slieet having poor coating adliesion, a significant difference of three ti~iies(3 0) or more of measitt~emev~a~rti ation needs to be provided bct\veen tlie iiieasurement values of the h\ro. [0009] As the analysis time for the determination is increased, the length of tlie steel sheet tliat has passed from the start to tlie end of the determination is i~icreased. When tlie manufactoring line is increased in speed, thc~t~ecessasrtye el sheet length for the determination is further i~icreased. When the length is excessively increased, quality assurance on the entire length of the coil becomes difficult, arid rapid feedback to the operational conditions becomes difficult. In order to enable measurement within a sho~tetri me, the improvement in the signal intensity and the SIN ratio is necessaly. In addition, steel sheet vibrations are increased due to all increase in speed, and there is a greater need for reducing tlie effect of the steel sheet vibrations on signals than in the related at?. [OO 101 Patent Document 6 discloses a technique for reducing an effect of steel sheet vibrations. In Patent Document 6, an i~~cideXnt- ray beam is incident on a multi-layer film mirror to be collimated. As a result, difiacted X-rays generated by irradiating the coating layer of a steel sheet surface with the incident X-ray beam are collimated. Therefore, even in a case where the distalice beheen the difiaction position of the X-rays and a detection system is changed due to vibrations of the steel sheet, there is an advantage in that the detected intensity of the diffracted X-rays is stabilized. [OOI 11 Tlie effect of the inulti-layer film mirror is also described in Non-Patent Docoment I. An example, in \vhich a inulti-layer film mirror and a parallel slit are used in order to eff~ciently colli~nated ivergent beams emitted from an X-ray source in a laboratory, is disclosed. [Prior AI? Docu~ne~it] [Patent Document] [0012] [Patent Document I] Japanese Unexamined Patent Application, First Publication No. S52-21887 [Patent Document 21 Japanese Unexatninecl Patent Application, First Publication No. HO5-45305 [Patent Document 31 Japanese Unexalnined Patent Application, First Publication No. H09-33455 [Patent Document 41 Japanese Unexamined Patent Application, First Publication No. H07-260715 [Patent Document 51 Japanese Unesar~oinedP atent Application, First Publication No. H04-I 10644 [Patent Doculnent 61 Japanese Unexnmined Patent Application, First Publication No. 2002-16881 1 [Non-Patent Docu~nent] [00 131 [Non-Patent Document I] "Advances in X-Ray Analysis 31", Pll to 27, issued in 2000 by ACNE Gijotsu Center Inc. [Disclosure of the Invention] [Problems to be Solved by the Invention] [0014] The present invention has been made taking the foregoing problems into consideration, and an object thereof is to provide an on-line coating adhesion determination apparatus of a galvannealed steel sheet, which can follo\v a further increase in the speed of a manufacturing line, and a galva~~nealestde el sheet matoufacturing line. [Means for Solvirig the'Probte~o~] [OO 151 The present inventors had intensively and repeatedly conducted researcl~f ocusing on tl~e fact that a background intensity is lo\\, and flat (is approximately horizontal) in a range iio which a difiaction angle 20 is on a lo\\, angle side. As a result, it was found that on a low angle side corresponding to a crystal lattice spacing d of 1.5A or higher, a plurality of X-ray diffraction peaks for a single phase are present. The inventors had I-epeatedly examined the quantitativeness of the peak intensities, and as a result, identified a peak for each phase, which has excellent quantitativeness and has lo\\' backgroiind itltensit)t. Moreover, it \\,as found that, by using a value obtained by subtracting a background intensity from the intensity of X-ray difiaction peak corresponding to a crystal lattice spacing d of 1.914A, the tltick~iesso f a r.fl phase, wliich affects the coating adhesion of a galvannealed steel sheet, call be nieasored with gootl accuracy. [OOI 61 Subsequently, the present inventors proceeded to exatnine tlie realization of tlie tecltniqoe. In order to apply the tecliniqoe to a ma~iofacturingl i~ieh aving high sheet threading speed for the steel sheet, pmblerns of steel sheet vibrations during slieet threading need to be solved. Under the tltougltt that a parallel beam optical system has to be l~setal s an optical systern io order to reduce the effect of steel sheet vibrations, a ~iiethodo f detecting a Fe-Zn phase low angle peak corresponding to a crystal lattice spacing d of 1.5A or higher, in the parallel beam optical systelit with high sensitivitjl \\,as intensi\rely and repeatedly examined. As a result, first, regarding tlie specifications of an X-ray tube, selectio~ot f an output, a focal size, an extraction angle, and an extraction method is impo~tant for sensitivity enhancemerit. Nest, the specifications of an optical systetn for irradiating a sample \\.it11 a beam erititted frorn tlie X-ray ttrbe and efficiently guiding the beant to a detector were examined. As a result, it was found that the detectiori efficiency particularly in an incidence optical systetu can be enhanced by appropriately setting a captore angle and reflectance. Here, the present inventors repeatedly condocted a systentatic experiment by changing such parameters, and as a result, found that on the premise of a parallel beam optical system, a desired diffraction peak can be detected wit11 good sensitivity by designing a X-I-ay tihe and the optical systeln so as to allow two pararnetels including "emitted beam luminance" and "widtlt-direction gain" to be higher than specific lower limits. Therefore, the present inventors produced an on-line X-ray diffraction apparatus \r~Iiiclts atisfied tlie above conditions and installed the apparatus at a position at which the sum of a slieet tliick~tessc hange and steel sheet vibrations was within *3 mmltt between an alloying fi~roacea rid coiling in a cootinoous gal\'anizirig line. The present inventors found that on-line adhesion determination of a galvan~tealed slieet can be actually performed with good accuracy within a short period of tinie and completed the present invention. [00 171 The present invention has been made on the basis of the findings, and the gist is as follows: (I) That is, according to an aspect of the present inventioo, an on-line coating adhesion determination apparatus of a galvannealed steel sheet, includes: an X-ray tube which irradiates a galvattnealed steel sheet tliat travels on a transpo~tatiorlii ne, wit11 X-rays; an optical systeln wliiclt allows the X-rays emitted from the X-ray tube to irradiate tlie galvannealed steel sheet as a parallel beam and be diffracted; and a detector \\~Iiiclmt easores an intensity of the difiacted X-rays and is installed at a position at which the X-ray diflyaction peak corresponding to a crystal lattice spacing d of 1.5A or higher is detected, in whiclt an emitted bean1 lurttinance of tlie X-rays is 20 \ v / I ~ IorI ~ ~ liiglic~; and tlie \\,idtli-direction gain of the X-rays in tlie optical systcm is 0.15 or higher. [00 l S] (2) In the on-line coating adliesion determination apparatus of a galvannealed steel slieet described in (I), tlie detector may be installed at a position of a diffractio~ia ngle at whicli tlie X-ray difiaction peak con.cspo~itlingto a crystal lattice spacing d of 1.914A is detected. [OO 191 (3) In the on-line coating adhesion determination apparatus of a galvannealed steel sheet described in (I) or (2), as the X-ray tube, an X-ray tube in \\~liiclia n energy of tlie X-rays incident on tlie galvannealed steel slieet is lo\\ser than an excitation energy of Fe-Ko fluorescence X-rays, may be used. [0020] (4) According to another aspect of tlie present inventioti, a galvatiriealed steel slieet manofacturing line includes: installing tlie on-line coating adliesion determination apparatus described in any one of (I) to (3), at a position at \vhicIi the sum of tlie sheet thickness change and steel sheet vibrations is within .t3 tnm between an alloying furnace and coiling. [Effects of the Invention] [OOZ I] By applying the on-line coating adliesion determination apparatus of a galvannealed steel sheet of the present inventio~id, etemiination of good adliesion and poor adliesion can be achieved within a short period time. Therefore, even when tlie sheet threading speed of a steel slieet in a manufacturing line is further increased, on-line measurement can be perfor~nedo ver tlie entire length of a coil with good accoracy. In addition, by quickly feeding tlie results back to operational conditions, excessive alloying or non-alloying car1 be prevented beforeliand. As a result, this significantly contributes to impmvement of yield and quality assurance even during high-speed slieet threading. Tlierefore, a galvannealed steel slieet with excellent coating quality can be stably sipplied to custome~sa t low cost. [Brief Description of tlie Draivings] [0022] FIG. I is a schematic view showing a focal size, an extraction angle, an extraction metliod, and an actual focal size of an X-ray tube in an on-line coating adhesion determination apparatus according to an enibodi~nento f tlie present invention. FIG. 2 is a schematic vie\\, showing iliain parts of tlie on-line coating adliesion deter~niiiationa pparatus according to the eiiibodiment of the present io\~ention. FIG. 3A is a vie\!, of tlie arrangement of an optical system on all incidence side in a case wliere solar slit is used, in \\4iicli (a) is a side vie\\: and (b) is a view ol'a beam surface. FIG. 3R is a vie\\, of the arrangement of tlie optical system on tlie incidence side it1 a case wliere a tnolti-layer film parabolic mirror and the solar slit are used, in \\,liicli (a) is a side vie\\,, and (b) is a vie\\, of a beam surfacc. FIG. 4 is a view ofthe arrangeinei~to f an optical systein on a light-receiving side, in which (a) is a side vie\\: and (b) is a view of a bentn surface. FIG. 5 a planar schematic vie\\, showing inain parts of tlie solar slit. FIG. 6 is a side scheniatic view showing the function of the multi-layer film parabolic niirror. FIG. 7 is a schematic view showing an example of the on-line coating adhesion determination apparatus according to the present invention. FIG. 8 is a schematic view showing an on-line coating adhesion detennination apparatus according to the related ait. FIG. 9 is a view sl~o\vingth e relationship between an emitted beam luininance and a width-direction gain in the on-line coating adhesion determination apparatus according to the embodiment of the present invention, and is a graph for comparison behveen Invention Exainples and Comparative Examples. FIG. 10 is a graph sho\ving the effect of steel sheet vibrations in the on-line coating adl~esiond etermination apparatus according to the einbodiment of tlie present invention. FIG. I 1 slio\v results of examination on the relationship behveen a r phase diffracted ray intensity measured by the on-line coating adhesion deterniination apparatus according to the present invention, and off-line coating adliesion test results. [Embodiments of tlie Invention] 100231 Hereinafter; an on-line coating adhesion detennination apparatus of a galvannealed steel sheet according to an embodiment of the present invention (hereinanel; so~netilnesi inply referred to as a deterinination apparatus according to this emboditnent), and a galvannealed steel slieet manufactiiring line in \\!11ich tlie apparatus according to the ernbodinlent of the present invention is installed and a high-speed operation is enabled (hereinafter, sometintes simply referred to as a tnanufacturing line according to this embodiment) will be described in detail witli reference to the drawings. 100241 The deterinination apparatus according to this embodiment is a ineasurelneiit apparatus \\rhich measures the thickness of a predetermined phase contained in an Fe-Zn alloy phase of tlie galvannealed steel sheet, and includes an X-ray tube which irradiates the galvannealed steel sheet witli X-rays, an optical system fio~omt he X-ray tube to a detector, and the detector wl~iclim easures the intensity of diffracted X-rays obtained through the X-ray imatliation. Using a parallel beam optical system as the optical system, X-rays are allowed to be incident on the galvannealed steel sheet ant1 be diffl-acted. In atldition, the detector is installed at a position couesponding to a diffraction angle at which X-rays dirraction peak corresponding to a crystal lattice spacing d of l.5A or higher are detected. In addition, the emitted beam luminance of the X-rays is 20 ~11n1no'r highel; and the width-direction gain of the X-rays in the optical system is 0.15 or higher. [0025] Hereinafier, an X-ray diffraction method applied to the determination apparatus according to this emboditnent will be described. The X-ray diffraction method applied to the determination apparatos according to this emboditnent incl~~dierrsa diating a polycrystalline satnple wit11 characteristic X-rays and measuring the reflection intensity at a specific diffraction arlgle and is classified into the Debye-Scherrer method. In addition, an X-ray difiaction apparatics which can be applied to the determination apparahis according to this embodiment is constituted by an X-ray tube which generates an X-ray beam, various slits for restricling the divergence of the X-ray beam, a detector, a light-receiving slit, a count recording device, and the like. [0026] The X,ray tube \vhich can be used in this elnbodi~nengt enerates thennal electrons by allowing current to flotv through a filament, generates X-rays by allowing the thermal electrons to accelerate at a high voltage of tens of kilo voltages and strike a metal target, and extract the generated X-rays through a beryllium windowv. The metal target of the X-ray tube is selected in consideration of absorption of X-rays by a specimen and measurement accoracy, and Ctl, CI; Fee, Co, Mo, \V, and the like are used. A~norlgth ese, Cu, CI; and Co are patticularly preferable due to excellent versatility. The generated X-rays include, as well as Ka rays as an object, Kp rays and white X-ray components and thus need to be conve~ted into tnonochromic light by rernoving such components. Conve~sioo~fl the X-ray beam into n~onochromicl ight is performed by inserting a Kp filter made of a metallic foil in front of the light-receiving slit or by itsing a monochromator. Furthel; a pulse height analyzer may also be combined or a collirnation system using an X-ray colli~natorm ay also be eniployed. [0027] As the slit for restricting the divergence of the X-ray beam, a solar slit for restricting the diverge11ce of the X-ray beam in a vertical direction and a divergence slit for restricting the angle of divergence of a san~plein a horizontal plane is preferably used. Diffracted X-rays generated by irradiating a material surface with tlie X-ray beam are collected via the light-receiving slit, and are detected by the X-ray detector fi~~thveira the solar slit and a scattering slit socll that the intensity thereof is measured. [002S] Nest, this embodiment will be described in more detail. First, the X-ray tube used in the on-line coating adhesion determination apparatus of the galvannealed steel sheet according to this embodiment will be described. As tlie X-ray tttbe, a sealed-type X-ray tube is preferably used. As the X-ray source, as well as the X-ray tube, there is a rotating anticathode-type X-ray generating device, wliicl1 is advantageous in terms of high outpttt. Iio\\reve~; in a case of being used in the galvat~nealeds teel sheet manrfacturit~gli ne, tnaintenance and management of a vacuum system and the like are comples. Therefore, the X-ray tihe is appropriate. As the sealed-type X-ray tube, any of a fluorescence X-ray tube and a diffracted X-ray titbe may be used. Ho\vever, the difiacted X-ray tube \\~hichh as a small focal size and high luminance is more appropriate. Exatnples of the sealed-type X-ray tube are shown in Table I. The fluoresce~~Xce-r ay tube has a relatively greater focal size than that of the difft-acted X-ray tube, and tubes of Nos. 1 to 3 in Table 1 correspond to the fluorescence X-ray tobe. Tubes of Nos. 4 to 15 in Table I correspond to the diffracted X-ray tube. In addition, a focal point luminance in Table I is a value obtained by dividing an output (W) by the area (tnmn2) of a focal point. [0029] [Table I] [0030] Regarding the specifications of tlie X-ray tube according to this embodiment, in addition to an outpt~ts, election of a focal size, all extraction angle, and an extraction o net hod is itnpo~tantf o~ sensitivity e~~l~ancemenFt.IG . I sl~o\\'st he relationshi() betweell the focal size, the extractiorl angle. the extractio~im ethod, the actual focal size after estraction in the tliKracted X-ray tobe. As shown in 1:IG. I, inside the X-ray tube, a filament 10, and a metal target I 1 disposed to bc separated from the filament 10 are provided. By allowing current to flo\\l tl~rought he filament 10, thermal electrons are gei~erateda, nt1 the generated themlal electrons are allowed to strike the metal target I I , thereby generating X-rays. A focal point 12, which is a region struck by the thermal electron, is formed on the metal target 11. The shape of the focal point I2 is a shape close to a pro.jected shape of the filament 10 on the metal target I I, and in the exantple shown in FIG. 1, is a substantially rcctangular shape having a width of a (mm) in a lateral direction, and a length of b (mm) in a longitudinal direction. When a perpendicular line is drawn from the filament 10 to the metal target I I , extraction angles ml and m2 are approximately 6" with respect to a plane perpendicular to the perpendicular line. [003 I] Regarding the inclination direction of the extraction angles In1 and in*, as sho\vn in FIG. 1, the inclination direction may be set along the \\,idth direction of the focal point 12, and the inclination direction may be set along the longitudinal direction tliereof. The extraction method includes "point extraction" in wvliich the cross-sectional shape of the X-ray bean1 is close to a square shape, and "line extraction" in \\.,. .O nly solar slit "A" ... Solar slit and multi-layer film parabolic mirror "B" ... Solar slit and pyrograpliite "C". .. Solar slit and flat type multi-layer film mirror [0079] As the optical element of the light-receiving optical system, the solar slit was used. As the detector, the following was used. Tlle types of detectors are described along with s)~mbols in Table 38. [OOSO] "S-PC" ... Sealed type gas propo~tional coltliter "SDD". . . Solid state detector "SC" ... Scintillation counter [OOSI] The obtained diffraction signals of the Fe-Zn phase were evaluated from the following vie\\fl)oints. [0082] Strength (cps): A value obtained by subtracting the background intensity from the peak intet~sityw as obtained as the intensity using a steel sheet in which Fe (%) in tlie coating layer was 9.5%. The backgrou~~wda s set to a straight line connecting both ends of tlie peak. The ineasurement titne was 0.1 sec. [OOS3] Determination tiole (sec): The intensities ofthe steel sheet in \vhich Fe (%) in tlte coating layer was 9.5% arid a steel sheet ill which Fe (%) was 10.5% were compared, and measure~netlt time necessary for allowing the difference therebehveen to become three times the measurement erron (tileoretical standard deviation) \\,as obtained. In a case of measuring the peak intensity of a r phase, the determination time corresponds to measurement time necessary for detel.mination of pass or fail of adhesion. [OOM] Vibratio~la cceptability (tnm): By using the steel sheet in which Fe (%) in the coating layer was 9.5%, a change in the peak intensity was exatnilled while changing the santple position, and an acceptable degree of displacement due to vibrations \\,as evaluated. An esa~npleo f results is shown in FIG. 10. In this case, it is determined that vibrations of +3 lntn can be acceptable. [OOSS] The results are s11o\vn in Tables 3A to 3D. In Nos. I to 28, the specifications of tlte X-ray tube and tlie optical systetn in Invention Exatnples were designed to increase the emitted beam luminance and the width-direction gain compared to Comparative Examples. The relatiortsltip is shown in FIG. 9. Here, when signal characteristics of Table 3 are compared to each othel; compared to Comparative Examples, in lnventio~iE xamples, the signal intensity is higli, tlte determination time is short, and an acceptable degree of vibrations is *3 mln. As a result, the measurement time for high-speed sheet threading is reduced, and measurement can be performed \vithout problems even when vibrations become intense. That is, follo\\~abilityfo r higli-speed operations is high. [00S6] Nos. 29 to 3 1 are measure~nent examples of the higli-angle-side Fe-Zn phase peak according to the related art. Althoogli the signal intensity is higli and steel slieet vibrations are acceptable, there is an original problem of peak separatio~o~f each phase, and the difference between sarnples having different Fe (%) ill the coating layel-s cannot be accurately determined. [0087] [Table 3Al I I - - X-lay tube specitications (*I) Extraction angle 6" [0088] [Table 381 30 31 Cr Cr Fluorescence Fluorescence 2.8 2.8 7 7 7.5 7.5 7 7 7 7 57 57 ("2) A: multi-layer film mirror (parabolic surface shape), B: graphite, C: multi-layer fil~nn iirro~ (flat surface shape) (*3) Distance L between slit and sample - [Table 3C] o Beam efficiency index Width-direction gain Width . length of X-ray irradiation of sample (mm) Focal point luminance corrected value Width ~ l r n n ~ ~ Emitted beam luminance Length \/mm2 [0090] [Table 3D] ($4) I-Iigh-angle peak has high intensity but has deteriorated SN. [0091] (Example 2) The determination apparatus according to this embodiment \\,as iristalled in tlie galvannealed steel slieet manufacturing line. The installation position is a horizontal pass after tlie completion of alloying and a roll coiling section. The configuration ofille apparatus is as sIio\vn in FIG. 7. The specifications ofthe apparatuses are as sliowti in No. 6 of Table 3. [0092] The galvannealed steel sheet was man~ifactored in the manufacturing line at a line speed of 180 mpm. During the manufactoring of the galvannealed steel slieet, an alloying temperatore was intentionally changed from an appropriate alloying temperature to an excessive alloyit~gte mperature to cause a good adliesion portion and a defective portion to be present in a single coil. This test was repeatedly conducted on three coils. Samples \vere obtained from a front portion, a middle portion, and a tail portion in tlie coils, and an off-line adhesion test was conducted. The grades of adl~esionin clude an A grade (pass), a B grade (pass although the grade is close to the borderline of pass and fail), and,a C grade (fail although the grade is close to the borderline of pass and fail). Tl~esa mples were subjected to a constant potential electrolysis method to peel tlie coating layers and allo\\, only a r phase single layer to remain, and the diffracted ray intensity of tlie r phase was obtained off-line. [0093] On the other hand, during the iiiamifacturing of the coils, by operating the determination apparatus according to this embodiment shown in FIG. 7, tlie difft-acted ray intensity of the r phase was oieasuretl on-line. The results are shown in FIG. 11 in which this is plotted by the vertical axis and the diffracted ray intensity of the r phase single layer obtained off-line is plotted by tlie horizontal axis. 30 - 31 S-PC S-PC 100 100 127.1 139.1 1.279 1.222 6 l- 900 300 ($4) ($4) 13 13 Comparative Example Comparative Example It can be seer1 from PIG. I I that even in a case where the galvannealed steel sheet is subjected to a liigh-speed operation at a line speed of 180 mpm, the determination apparatus according to this embodiment can accl~ratelpd eter~ninec oating adhesion similarly to off-line evall~ation. 100941 Wllile the preferable embodiments of the present invention have been described in detail \vith reference to the drawings, the present invention is not limited to the embodiments. It should be noted by those skilled in the art to wl~ichth e present invention belongs that various changes and modification esa~nplesc an be made in the scope of tlie technical spirit described in the appended claims, and these examples naturally belong to the tecl~nicalr ange of the present invention. [Industrial Applicability] [0095] According to the present invention, a galvannealed steel sheet \\,it11 stable quality can be stably s~~pplieadt l ow cost, and tlii~sth e spread of vehicles with excellent antirust properties is fi111hera ccelel-ated. This is connected to tlie enhancement in tl~eli fe-span and safety of vehicles and contrib~~tteos the in~provementin the global ei~virotl~nefnrot1 11 the viewpoint of saving resources. Therefore, industrial utility is estren~elyh igh. [Brief Description of the Reference Symbols] [0096] 21: X-RAY SOURCE (X-RAY TUBE) 22: INCIDENCE OPTICAL SYSTEM (OPTICAL SYSTEM) 24: DETECTOR Amendment of the claims under Article 34 CLAIMS 1. (Unchanged) An on-line coating adhesion detemlination apparatns of a galvannealed steel sheet, comprising: an X-ray tnbe which irradiates a galvannealed steel sheet that travels on a transportation line, with X-rays; an optical systenl which allo\vs the X-rays emitted from the X-ray tnbe to irradiate the galvannealed steel sheet as a parallel bean1 and be diffracted; and a detector n,hich measures an intensity of the diaacted X-rays and is installed at a position at wvhich a X-ray diffraction peak corresponding to a crystal lattice spacing d of 1.5A or higher is detected, wherein an emitted beam lulninance of the X-rays is 20 \4'Imm2 or highel; and a width-direction gain of the X-rays in the optical system is 0.15 or higher. - 2. (Amended) The on-line coating adhesion determination apparatus of a galvannealed steel sheet according to claim 1, wherein the detector is installed at a position ef-a-&fiaetio~afigle at mhich thc a X-ray diaaction peak corresponding to a crystal lattice spacing anv one of (I of 1.507 A, 1.536 A, 1.623 lf,.~720 A, 1.833 A,..1.899 A, 1.914A, 1.971 A. 2.363 A. 2.593 A, 2.770 &= A. 4.109 A,5.535 A, or 6.351A is detected. 3. (Unchanged) The on-line coating adhesion determination apparatns of a galvannealed steel sheet according to claim 1 or 2, wherein, as the X-ray tube, an X-ray tube in ~vhicha n energy of the X-rays incident on the galvannealed steel sheet is lower than an excitation energy of Fe-ICn fluorescence X-rays, is used. 4. (.4mended) A galvannealed steel sheet manufacturing line comprising: the on-line coating adhesion determination apparatus according t o m one of claims 1 to 3 which is installed at a position at which a sum of a sheet thickness change and steel sheet vibrations is within 13 nlm between an alloying fitr~lacea nd coiling.